Trouble with evap and egr monitors??
#1
04-21-2013 | 03:26 PM
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Joined: Apr 2013
Posts: 1
Trouble with evap and egr monitors??
Hey guys, first post here and would like to thank you for your help ahead of time! I have a 99 camaro 3.8 which I threw a check engine for a bad cat. (P0420) so I have gotten the cat replaced and cleared the code. I have driven about 700 miles over 3 weeks and the evap and egr monitors still haven't completed. I'm running out of time with my temp registration from the DMV. Looking for your thoughts on this?! Thanks again.
#2
04-21-2013 | 04:11 PM
Overdrive Member
Joined: Nov 2006
Posts: 4,042
From: IL
This might help...
Document ID# 356984
1999 Chevrolet/Geo Camaro
DTC P0420 Catalyst System Low Efficiency
Refer to HO2S Sensors .
Circuit Description
To control emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx), a three-way catalytic converter is used. The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO present in the exhaust gas, converting them into harmless water vapor and carbon dioxide. The catalyst also reduces NOx, converting it to nitrogen. The converter also has the ability to store excess oxygen and release the stored oxygen to promote these reactions. This oxygen storage capacity (OSC) is a measurement of the catalyst's ability to control emissions. The PCM monitors this process using a heated oxygen sensor (HO2S) located in the exhaust stream past the three-way converter. When the catalyst is functioning properly, the HO2S 2 is slow to respond to a large change in the HO2S1 signal. When the HO2S 2 responds quickly to a large change in the HO2S 1 signal, the OSC and efficiency of the catalyst is considered to be bad and the MIL will be illuminated if subsequent tests also indicate a failure.
Conditions for Running the DTC
Meet conditions for engine warm up. Use the scan tool catalyst data list in order to verify the following.
No VSS, EVAP, Misfire, HO2S, EGR, ECT, MAF, ETC, IAT, MAP, CMP, CKP Sensor, Fuel Trim, or Fuel Injector DTCs set.
Engine has been running longer than 10 minutes.
Engine coolant temperature (ECT) is above 76°C (169°F) and below 124°C(255°F).
Baro is above 75 kPa.
Vehicle is in Closed Loop.
Intake air temperature (IAT) is above -20°C (-4°F) and less than 100°C (212°F).
Battery voltage above 10.7 volts.
Warm up the catalyst.
Fully open hood.
Transmission is in park (automatic) or neutral (manual).
Set the parking brake.
Press and hold service brake.
Each time the engine is started the diagnostic can run up to 18 times. After the ten minute run time, and before the diagnostic runs the first time, the engine must run an additional 5 minutes between 1500 and 2000 RPM. Any additional tests on the same key cycle, the RPM must be between 1500 and 2000 RPM for 1 minute.
To activate the diagnostic; Return to idle and put the vehicle in drive (automatic) or depress the clutch (manual).
Test the catalyst.
Place the transmission in drive (automatic) or neutral and depress the clutch (manual).
Within 60 seconds the air fuel ratio will go rich below 14.1 for up to 5 seconds, then it may go lean above 15.3 for up to 5 seconds.
Using the scan tool check and see if DTC P0420 has passed or failed this key cycle
Conditions for Setting the DTC
The PCM determines that the catalyst's oxygen storage capacity is below a threshold considered acceptable.
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic test has been run and failed.
The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
Conditions for Clearing the MIL/DTC
The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
The DTC can be cleared by using the scan tool.
Diagnostic Aids
Check for the following conditions:
The PCM WILL NOT ENABLE the catalyst test until following conditions are met:
Engine speed is plus or minus 250 RPM from desired idle.
Throttle Position (TP) is less than .5%.
Short term integrator is between -20% and +20%.
The catalyst test WILL ABORT if the vehicle falls out side the conditions listed below while the test is running:
Engine speed is plus or minus 250 RPM from desired idle.
Throttle Position (TP) is less than .5%.
Short term integrator is between -20% and +20%.
The catalyst test may abort due to a change in engine load (i.e., A/C, coolant fan). If this problem occurs use the scan tool to force the cooling fans on return to step 3 in the table then repeat the test.
Important
When using the scan tool to force the cooling fans on use the next list and previous list soft keys to enter the catalyst data list. If the catalyst data list is not entered this way the cooling fan control will be canceled.
The number of attempted tests is limited to 18 per key cycle.
More than 6 tests may have to be attempted to get 6 completed tests. An aborted test counts as an attempted test.
If 18 tests have been attempted, and a decision has not been made this key cycle then turn the key OFF for 30 seconds. Start the engine and perform the Conditions for Running the DTC - including the 10 minute run time.
After returning to an idle the HO2S 1 signal may stay rich or lean for several seconds causing the test to be delayed.
Poor connection at PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the fault.
Test Description
Numbers below refer to the step numbers on the diagnostic table:
The powertrain OBD system check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable.
If any other DTCs are set, diagnose those DTCs first. A fault in a component can cause the converter to appear degraded or may have caused its failure.
Clearing the DTCs allows the catalyst test to be attempted 18 times and completed up to 6 times this key cycle. If the A/C is ON the diagnostic may not run. The engine must be warmed-up. The converter needs to be warmed-up by raising the engine speed above idle for the specified time prior to each attempted test. Check and see if DTC passed or failed this key cycle. If the DTC does not pass or fail look for a possible reason that would cause the test to abort.
This step includes checks for conditions that can cause the three-way converter to appear degraded. Repair any problems found before proceeding with this table.
If the three-way converter needs to be replaced, make sure that another condition is not present which could damage the converter. These conditions may include: misfire, high engine oil or coolant consumption, retarded spark timing, weak spark or a plugged/leaking injectors. Correct any possible causes of converter damage before replacing the converter.
DTC P0420 - TWC System Low Efficiency
Step
Action
Values
Yes
No
1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check performed?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check
2
Are any other DTCs set?
--
Go to the applicable DTC first
Go to Step 3
3
Important
If the A/C is left on the following diagnostic may not run.
Turn OFF the A/C.
Use the scan tool in order to clear the DTCs.
Start the engine and wait until the vehicle is fully warmed up-idle for at least 10 minutes, then operate the vehicle above 1500 RPM for 5 additional minutes. (One minute for each additional attempt at 1500 RPM on the same ignition cycle). The vehicle may be driven for the additional 5 minute run time.
Fully open the hood.
Operate the vehicle within the Fail Record conditions.
Important:
If more than 6 tests have been attempted and the DTC has not passed or failed this ignition the test may be aborting. Refer to Diagnostic Aids.
The test may need to be completed up to 6 times in order to pass or fail.
Does the scan tool indicate the DTC ran and passed this ignition?
--
System OK
Go to Step 4
4
Visually and physically inspect the three-way catalytic converter for damage.
Inspect for the following:
Dents.
Severe discoloration caused by excessive temperatures.
Holes.
Internal rattle caused by damaged catalyst substrate.
Also, ensure that the three-way catalytic converter is a proper original equipment manufacturer part.
Did you find damage?
--
Go to step 9
Go to step 5
5
Visually and physically inspect the exhaust system for leaks.
Did you find a problem?
--
Go to Step 7
Go to Step 6
6
Visually inspect for the following:
Oxygen sensors for damage.
Oxygen sensors wiring harness for damage.
Did you find a problem?
--
Go to Step 8
Go to Step 9
7
Repair the exhaust system as necessary.
Did you complete the repair?
--
Go to Step 10
--
8
Replace the oxygen sensor or repair the wiring as necessary. Refer to Heated Oxygen Sensor (HO2S) Replacement or Wiring Repairs .
Did you complete the replacement?
--
Go to Step 10
--
9
Notice
In order to avoid damaging the replacement three-way catalytic converter, correct the engine misfire or mechanical fault before replacing the three-way catalytic converter.
Replace the three way catalytic converter. Refer to Catalytic Converter Replacement in Engine Exhaust.
Did you complete the replacement?
--
Go to Step 10
--
10
Important:
If the A/C is left on the following diagnostic may not run.
With a scan tool, clear DTCs.
Turn OFF the A/C.
Fully open the hood.
Operate the vehicle within the Fail Record conditions.
Important:
If more than 6 tests have been attempted and the DTC has not passed or failed this key cycle the test may be aborting. Go to diagnostic aids.
The test may need to be completed up to 6 times in order to pass or fail.
Does the scan tool indicate the DTC ran and passed this key cycle?
--
Go to Step 11
Go to Step 4
11
Does the scan tool indicate any DTCs that you have not diagnosed?
--
Go to Applicable DTC Table
System OK
Document ID# 356984
1999 Chevrolet/Geo Camaro
Document ID# 356984
1999 Chevrolet/Geo Camaro
DTC P0420 Catalyst System Low Efficiency
Refer to HO2S Sensors .
Circuit Description
To control emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx), a three-way catalytic converter is used. The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO present in the exhaust gas, converting them into harmless water vapor and carbon dioxide. The catalyst also reduces NOx, converting it to nitrogen. The converter also has the ability to store excess oxygen and release the stored oxygen to promote these reactions. This oxygen storage capacity (OSC) is a measurement of the catalyst's ability to control emissions. The PCM monitors this process using a heated oxygen sensor (HO2S) located in the exhaust stream past the three-way converter. When the catalyst is functioning properly, the HO2S 2 is slow to respond to a large change in the HO2S1 signal. When the HO2S 2 responds quickly to a large change in the HO2S 1 signal, the OSC and efficiency of the catalyst is considered to be bad and the MIL will be illuminated if subsequent tests also indicate a failure.
Conditions for Running the DTC
Meet conditions for engine warm up. Use the scan tool catalyst data list in order to verify the following.
No VSS, EVAP, Misfire, HO2S, EGR, ECT, MAF, ETC, IAT, MAP, CMP, CKP Sensor, Fuel Trim, or Fuel Injector DTCs set.
Engine has been running longer than 10 minutes.
Engine coolant temperature (ECT) is above 76°C (169°F) and below 124°C(255°F).
Baro is above 75 kPa.
Vehicle is in Closed Loop.
Intake air temperature (IAT) is above -20°C (-4°F) and less than 100°C (212°F).
Battery voltage above 10.7 volts.
Warm up the catalyst.
Fully open hood.
Transmission is in park (automatic) or neutral (manual).
Set the parking brake.
Press and hold service brake.
Each time the engine is started the diagnostic can run up to 18 times. After the ten minute run time, and before the diagnostic runs the first time, the engine must run an additional 5 minutes between 1500 and 2000 RPM. Any additional tests on the same key cycle, the RPM must be between 1500 and 2000 RPM for 1 minute.
To activate the diagnostic; Return to idle and put the vehicle in drive (automatic) or depress the clutch (manual).
Test the catalyst.
Place the transmission in drive (automatic) or neutral and depress the clutch (manual).
Within 60 seconds the air fuel ratio will go rich below 14.1 for up to 5 seconds, then it may go lean above 15.3 for up to 5 seconds.
Using the scan tool check and see if DTC P0420 has passed or failed this key cycle
Conditions for Setting the DTC
The PCM determines that the catalyst's oxygen storage capacity is below a threshold considered acceptable.
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic test has been run and failed.
The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
Conditions for Clearing the MIL/DTC
The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
The DTC can be cleared by using the scan tool.
Diagnostic Aids
Check for the following conditions:
The PCM WILL NOT ENABLE the catalyst test until following conditions are met:
Engine speed is plus or minus 250 RPM from desired idle.
Throttle Position (TP) is less than .5%.
Short term integrator is between -20% and +20%.
The catalyst test WILL ABORT if the vehicle falls out side the conditions listed below while the test is running:
Engine speed is plus or minus 250 RPM from desired idle.
Throttle Position (TP) is less than .5%.
Short term integrator is between -20% and +20%.
The catalyst test may abort due to a change in engine load (i.e., A/C, coolant fan). If this problem occurs use the scan tool to force the cooling fans on return to step 3 in the table then repeat the test.
Important
When using the scan tool to force the cooling fans on use the next list and previous list soft keys to enter the catalyst data list. If the catalyst data list is not entered this way the cooling fan control will be canceled.
The number of attempted tests is limited to 18 per key cycle.
More than 6 tests may have to be attempted to get 6 completed tests. An aborted test counts as an attempted test.
If 18 tests have been attempted, and a decision has not been made this key cycle then turn the key OFF for 30 seconds. Start the engine and perform the Conditions for Running the DTC - including the 10 minute run time.
After returning to an idle the HO2S 1 signal may stay rich or lean for several seconds causing the test to be delayed.
Poor connection at PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the fault.
Test Description
Numbers below refer to the step numbers on the diagnostic table:
The powertrain OBD system check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable.
If any other DTCs are set, diagnose those DTCs first. A fault in a component can cause the converter to appear degraded or may have caused its failure.
Clearing the DTCs allows the catalyst test to be attempted 18 times and completed up to 6 times this key cycle. If the A/C is ON the diagnostic may not run. The engine must be warmed-up. The converter needs to be warmed-up by raising the engine speed above idle for the specified time prior to each attempted test. Check and see if DTC passed or failed this key cycle. If the DTC does not pass or fail look for a possible reason that would cause the test to abort.
This step includes checks for conditions that can cause the three-way converter to appear degraded. Repair any problems found before proceeding with this table.
If the three-way converter needs to be replaced, make sure that another condition is not present which could damage the converter. These conditions may include: misfire, high engine oil or coolant consumption, retarded spark timing, weak spark or a plugged/leaking injectors. Correct any possible causes of converter damage before replacing the converter.
DTC P0420 - TWC System Low Efficiency
Step
Action
Values
Yes
No
1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check performed?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check
2
Are any other DTCs set?
--
Go to the applicable DTC first
Go to Step 3
3
Important
If the A/C is left on the following diagnostic may not run.
Turn OFF the A/C.
Use the scan tool in order to clear the DTCs.
Start the engine and wait until the vehicle is fully warmed up-idle for at least 10 minutes, then operate the vehicle above 1500 RPM for 5 additional minutes. (One minute for each additional attempt at 1500 RPM on the same ignition cycle). The vehicle may be driven for the additional 5 minute run time.
Fully open the hood.
Operate the vehicle within the Fail Record conditions.
Important:
If more than 6 tests have been attempted and the DTC has not passed or failed this ignition the test may be aborting. Refer to Diagnostic Aids.
The test may need to be completed up to 6 times in order to pass or fail.
Does the scan tool indicate the DTC ran and passed this ignition?
--
System OK
Go to Step 4
4
Visually and physically inspect the three-way catalytic converter for damage.
Inspect for the following:
Dents.
Severe discoloration caused by excessive temperatures.
Holes.
Internal rattle caused by damaged catalyst substrate.
Also, ensure that the three-way catalytic converter is a proper original equipment manufacturer part.
Did you find damage?
--
Go to step 9
Go to step 5
5
Visually and physically inspect the exhaust system for leaks.
Did you find a problem?
--
Go to Step 7
Go to Step 6
6
Visually inspect for the following:
Oxygen sensors for damage.
Oxygen sensors wiring harness for damage.
Did you find a problem?
--
Go to Step 8
Go to Step 9
7
Repair the exhaust system as necessary.
Did you complete the repair?
--
Go to Step 10
--
8
Replace the oxygen sensor or repair the wiring as necessary. Refer to Heated Oxygen Sensor (HO2S) Replacement or Wiring Repairs .
Did you complete the replacement?
--
Go to Step 10
--
9
Notice
In order to avoid damaging the replacement three-way catalytic converter, correct the engine misfire or mechanical fault before replacing the three-way catalytic converter.
Replace the three way catalytic converter. Refer to Catalytic Converter Replacement in Engine Exhaust.
Did you complete the replacement?
--
Go to Step 10
--
10
Important:
If the A/C is left on the following diagnostic may not run.
With a scan tool, clear DTCs.
Turn OFF the A/C.
Fully open the hood.
Operate the vehicle within the Fail Record conditions.
Important:
If more than 6 tests have been attempted and the DTC has not passed or failed this key cycle the test may be aborting. Go to diagnostic aids.
The test may need to be completed up to 6 times in order to pass or fail.
Does the scan tool indicate the DTC ran and passed this key cycle?
--
Go to Step 11
Go to Step 4
11
Does the scan tool indicate any DTCs that you have not diagnosed?
--
Go to Applicable DTC Table
System OK
Document ID# 356984
1999 Chevrolet/Geo Camaro
#4
04-21-2013 | 05:26 PM
April 2011 ROTM
Joined: Mar 2009
Posts: 21,770
From: Tokeland, Washington
ROTM Winner's Club
ahh ok you need to run it though a few cycles
General Motors Driving Cycle
Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 50°C (122°F) and within 6°C (11°F) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.
Idle. The engine must be run for two and a half minutes with the air conditioner on and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.
Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.
Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.
Decelerate. Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.
Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.
Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.
__________________
General Motors Driving Cycle
Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 50°C (122°F) and within 6°C (11°F) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.
Idle. The engine must be run for two and a half minutes with the air conditioner on and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.
Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.
Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.
Decelerate. Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.
Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.
Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.
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