Service Engine Soon (SES) Light On, Reduced Vehicle Performance, Acceleration and Top Speed (Replace Catalytic Converter and Brake Vacuum Booster Hose with Thermo Protection)

Some customers may comment on the SES light on and/or reduced vehicle power, acceleration and reduced top speed.

This condition may be caused by a restriction in the catalytic converter.

Follow the service procedure below for diagnosis and replacement of the catalytic converter.

1. For diagnosis of the catalytic converter, refer to Restricted Exhaust, SI Document ID #685978.
2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle SI Document ID #692668.



3. Disconnect the heated oxygen sensor (HO2S) electrical connector.
4. Remove the exhaust manifold pipe stud nuts.
5. Remove the rear catalytic converter bolts.
6. Remove the two rear converter hangers.
7. Remove the 3-way catalytic converter.
8. Remove the converter gasket and seal and discard.
9. Remove the heated oxygen sensor (HO2S) from the old converter using J 39194 Oxygen Sensor Wrench or equivalent and properly discard the old converter.

Important: The 3-way catalytic converter is serviced by replacing the entire assembly. Always replace the gasket at the front flange when servicing the 3-way catalytic converter assembly. Never install the original gasket.

10. Install the heated oxygen sensor (HO2S) into the new converter, P/N 10337610, using J 39194 Oxygen Sensor Wrench or equivalent.
11. Install a new exhaust manifold to converter pipe gasket, P/N 12565634.
12. Install a new converter pipe to muffler pipe gasket, P/N 10275205.
13. Install the converter to the vehicle.
14. Attach the two rear converter hangers.
15. Install the catalytic converter rear bolts.
16. Install the front catalytic converter nuts.

Tighten

•	Tighten the exhaust manifold pipe stud nuts to 32 Nm (24 lb ft).

•	Tighten the catalytic converter bolts to 45 Nm (33 lb ft).

17. Connect the heated oxygen sensor (HO2S) electrical connector.
18. Lower the vehicle.

Important: When replacing catalytic converter, P/N 10337610, you MUST REPLACE the brake vacuum booster hose with thermo protection sleeve, P/N 10336627.

19. Remove the brake booster vacuum hose and discard.
20. Install the new vacuum booster hose with thermo protection sleeve, P/N 10336627.
21. Inspect the exhaust system for leaks.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: