Service Update for Inventory Vehicles Only-Post Catalyst Oxygen (O2) Sensor - Inspect/Replace - Expires September 30, 2007

THIS SERVICE UPDATE INVOLVES VEHICLES IN DEALER INVENTORY ONLY AND WILL EXPIRE January 31, 2008.

This bulletin provides a service procedure to inspect and, if necessary, replace the Post Catalyst Oxygen (O2) Sensor on certain 2007 Chevrolet Impala, Monte Carlo; and 2008 Chevrolet Impala vehicles. These vehicles may have been built with an incorrect Post Catalyst Oxygen (O2) Sensor.

This service procedure should be completed on involved vehicles currently in dealership inventory as soon as possible, but no later than January 31, 2008, at which time this bulletin will expire.

A list of involved vehicles currently in dealer inventory is available on the "Service Update Bulletin Information" link under the "Service" tab in DealerWorld (US), and/or attached to the Dealer Communication (Canada, US), used to release this bulletin.

Important: Dealers are to confirm vehicle eligibility prior to beginning repairs by using the GM Vehicle Inquiry System (GMVIS). Not all vehicles within the above breakpoints may be involved.

Parts required to complete this service update are to be obtained from General Motors Service and Parts Operations (GMSPO). Please refer to your "involved vehicles listing" before ordering parts. Normal orders should be placed on a DRO = Daily Replenishment Order. In an emergency situation, parts should be ordered on a CSO = Customer Special Order.

Important: It is estimated that after inspection less than 1% of involved vehicles will require a Post Catalyst Oxygen (O2) Sensor replacement. Parts should only be ordered when the inspection determines that it is necessary to replace the Post Catalyst Oxygen (O2) Sensor.

Post Catalyst O2 Sensor Inspection and Replacement Procedure

Important: 2007 model year Chevrolet vehicles should be equipped with the ‘Delphi’ brand, P/N 12570149, Post Catalyst Oxygen (O2) Sensor. 2008 model year Chevrolet vehicles should be equipped with the ‘Denso’ brand, P/N 12608662, Post Catalyst Oxygen (O2) Sensor.

1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in SI.



2. Inspect the heated oxygen sensor bank 1 sensor 2 by pulling back the oxygen sensor protective sleeve (1). The wires should be the following colors:

-	Delphi P/N 12570149 - Used on Model Year 2007, Brown (2), Purple (1) and Tan (1).

-	Denso P/N 12608662 - Used on Model Year 2008, Black (2), White (1), and Blue (1).

3. If the inspection identifies that the vehicle was built with the incorrect sensor, replace bank 1 sensor 2 with the correct sensor as mentioned above. Refer to step 5 for the sensor replacement procedure, if necessary.
4. If the vehicle was built with the correct sensor, ensure that the protective sleeve is restored to its original position and lower the vehicle.
5. Remove the connector position assurance (CPA) retainer.
6. Disconnect the bank 1 sensor 2 electrical connector.
7. Remove the sensor from the catalytic converter.
8. Install the correct sensor as mentioned above to the catalytic converter.

Tighten
Tighten the sensor to 42 N·m(31 lb ft).

9. Connect the bank 1 sensor 2 electrical connector.
10. Install the CPA retainer.
11. Lower the vehicle.

For vehicles repaired under this service update, use: