Exhaust System - MIL ON/DTC P0420/Poor Performance
ENGINEERING INFORMATIONBulletin No.: 08-06-05-002
Date: March 05, 2008
Subject:
EI08085 - 2.0L, MIL Lamp On, DTC P0420, Exhaust Noise Poor Engine Performance (Engineering Information)
Models:
2005-2007 Chevrolet Cobalt SS Supercharged
2004-2007 Saturn ION Redline
with 2.0L Engine (VIN P - RPO LSJ)
Attention:
Proceed with this bulletin ONLY if the customer has commented about this concern AND the EI number is listed in GMVIS. If the customer has not commented about this condition or the EI does not show in GMVIS disregard the bulletin and proceed with diagnostics found in published service information. THIS IS NOT A RECALL - refer to Corporate Bulletin Number 04-00-89-053B for more details on the use of Engineering Information bulletins.
Condition
Some customers may comment on any of the following conditions:
^ Poor engine performance
^ Loud exhaust sound
^ MIL On (DTC P0420)
Cause
If a customer brings their vehicle in for any of these conditions complete the following steps before making any repairs:
1. Using the Tech 2(R) note any DTCs that have set.
2. Inspect the exhaust flex joint and note any corrosion cracks or damage.
3. Complete the following steps to check the exhaust system back pressure:
1. Remove the position 1 H02S.
2. Install the J 35314-A Back Pressure Gage in place of the position 1 H02S.
3. Start the engine.
4. Increase and monitor the engine speed at 2000 RPM.
5. Observe and note on the repair order the exhaust system back pressure reading on the gage.
6. Turn the engine off and place the ignition in the lock position.
7. Remove the J 35314-A and reinstall the position 1 HO2S.
8. Remove the position 2 HO2S.
9. Install the J 35314-A in place of the position 2 HO2S.
10. Start the engine.
11. Increase and monitor the engine speed at 2000 RPM.
12. Observe and note on the repair order the exhaust system back pressure reading on the gage.
13. Remove the J 35314-A and reinstall the position 2 HO2S.
4. Clear any DTCs.
5. Contact the engineer with the results from Steps 1-3.
^ If diagnosis finds the flex joint has failed or the converter is plugged replace the exhaust pipe/catalytic converter. Components will be requested back through the Warranty Parts Center (WPC).
^ If diagnosis does not indicate a failed flex joint or plugged converter continue to diagnose and repair using information found in Service Information (SI).
Warranty Information
For vehicles repaired under warranty and using this bulletin use the table.
Disclaimer