GM Service Manual Online
For 1990-2009 cars only

CAMPAIGN: OXYGEN SENSOR REPLACEMENT (CALIFORNIA)

SUBJECT: OXYGEN SENSOR REPLACEMENT (CALIFORNIA VEHICLES ONLY)

MODELS: 1991 C/K TRUCKS, M/L AND G VANS WITH 4.3L ENGINES AND CALIFORNIA EMISSIONS RPO NB2

General Motors has determined that CERTAIN 1991 C/K Trucks, M/L and G Vans with 4.3L engines (RPO LB4 - VIN Code "Z") and M Vans equipped with 4.3L (RPO LU2 - VIN Code "B") may be emitting non-methane hydrocarbons (NMHC) in excess of California emission standards. California emission standards were established to protect the public health and welfare from dangers of air pollution. Excess emission of NMHC may cause a vehicle to fail state mandated emission tests.

To correct this condition, dealers are to install a new exhaust oxygen sensor.

VEHICLES INVOLVED

Involved are CERTAIN 1991 C/K Trucks, M/L and G Vans equipped with 4.3L engines sold in California:

Plant Model From Through ----- ----- ---- ------- Baltimore (B) L MB500007 MB542303 Baltimore (B) M MB500010 MB543330 Pontiac East (E) C ME500953 ME546721 Pontiac East (E) K ME519156 ME546633 Fort Wayne (Z) C MZ500002 MZ539320 Fort Wayne (Z) K MZ501128 MZ539127 Oshawa (1) C M1503755 M1553017 Oshawa (1) K M1504497 M1550459 Lordstown (7) G M7500182 M7517057

The specific vehicles involved in this campaign have been identified by Vehicle Identification Number (VIN) Computer Listings. These listings are furnished to all involved dealers with the campaign bulletin. Dealers should confirm vehicle eligibility through VISS (Vehicle Information Service System or SERVICENET prior to beginning campaign repairs.

DEALER CAMPAIGN RESPONSIBILITY

All unsold new vehicles in dealers' possession and subject to this campaign must be held and inspected/repaired per the service procedure of this campaign bulletin before owners take possession of these vehicles.

Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of mileage, age of vehicle, or ownership, from this time forward.

Whenever a vehicle subject to this campaign is taken into your new or used vehicle inventory, or it is in your dealership for service in the future, you should take the steps necessary to ensure the campaign correction has been made before reselling or releasing the vehicle.

Owners of vehicles recently sold from your vehicle inventory are to be contacted by the dealer and arrangements made to make the required correction according to instructions contained in this bulletin. If the name and address of the owner of an involved vehicle was unavailable to GMC Truck Division at the time of campaign initiation, the dealer must determine the owner's name and address from the dealership sales records. Please provide this information directly on the second copy of the listing next to the applicable VIN so that our records may be updated and the appropriate notification mailed to the owner. This second copy should then be submitted to the address listed below in the previously supplied yellow campaign envelopes.

GMC Truck Division General Motors Corporation 101 Union Street Plymouth, Michigan 48170

OWNER NOTIFICATION

Owners will be notified of this campaign on their vehicles by GMC Truck Division (see copy of owner letter included with this bulletin). A listing of owner names and addresses has been furnished to the involved dealers to enable dealers to follow up with owners involved in this campaign. This listing may contain owner names and addresses obtained from State Motor Vehicle Registration records. The use of such motor vehicle registration data for any other purpose is a violation of law in several states. Accordingly, you are urged to limit the use of this listing to this campaign.

SERVICE PROCEDURE

1. Raise vehicle.

2. Disconnect oxygen sensor electrical connector by releasing locking tab.

3. Carefully back out oxygen sensor from exhaust pipe.

4. Install new oxygen sensor P/N 25105901, and torque to 41 Nm (30 ft. lb.).

5. Connect oxygen sensor electrical connector.

6. Lower vehicle.

7. Install Campaign Identification Label.

PARTS INFORMATION

Parts are to be obtained from General Motors Service Parts operation (GMSPO). To ensure parts are obtained as soon as possible, order them from GMSPO on a C.I.O. order with no special instruction code but order under an advise code (2).

Part Number Description Quantity ----------- ----------- -------- 25105901 Sensor Asm. - Exhaust Oxygen 1

WARRANTY INFORMATION

Dealers should submit a warranty claim on each vehicle completed under this campaign.

Labor Operation *Time Cause Number Description Allowance Code ---------------------------------------------------------------------- V9480 Install New Sensor 0.3 96

* For dealer to receive Administrative Time Allowance associated with this campaign, add 0.1 hour to the Labor Operation Time Allowance.

CAMPAIGN IDENTIFICATION LABEL

Each vehicle corrected in accordance with the instructions outlined in this Product Campaign Bulletin will require a "Campaign Identification Label." Each label provides a space to include the campaign number and five (5) digit dealer code of the dealer performing the campaign service. This information may be inserted with a typewriter or ball point pen.

Each "Campaign Identification Label" is to be located on the radiator core support in an area which will be visible when the vehicle is brought in for periodic servicing by the owner.

Apply "Campaign Identification Label" only on a clean, dry surface.

ADMINISTRATIVE PROCEDURE

Procedures covering this campaign are outlined in Section V of your dealership's "GMC Truck Warranty Claims Processing Manual" #P9119 Rev. 2/94.

Dear GMC Truck Owner:

General Motors has determined that certain 1991 GMC Truck Sierra Full Size Pickups, Safari, Vandura and Rally Vans equipped with 4.3L engines and California emission system may be releasing air pollutants which exceed California standards for non- methane hydrocarbons (NMHC). These standards were established to protect your health and welfare from the dangers of air pollution. Although this condition should not affect the driveability or performance of your vehicle, if not repaired, it may cause your vehicle to fail an emission inspection or Smog Check test when such tests are required under State law.

To correct this condition, your GMC Truck dealer will replace your exhaust emission oxygen sensor. This service will be performed for you at no charge.

Instructions for performing this service have been sent to your GMC Truck dealer, and parts are available. Please contact your GMC Truck dealer to arrange a service date as soon as possible. This procedure will take approximately 20 minutes to complete, but you should ask how much additional time your dealer will need to schedule and process your vehicle.

Your GMC Truck dealer is best equipped to provide service to ensure your vehicle is corrected as promptly as possible. However, if you take your vehicle to your dealer on the agreed service date and they do not service this condition on that date or within five days, we recommend you contact GMC Truck Consumer Relations. Consumer Relations will assist you and your dealer in getting your vehicle corrected. The telephone number of the Consumer Relations office is listed in your Warranty and Owner Assistance Information Manual.

After contacting your GMC Truck dealer and the Zone Office, if you are still not satisfied that we have done our best to remedy this condition without charge within a reasonable time, you may wish to write the Environmental Protection Division (EN-340F), United States Environmental Protection Agency, 401 M Street, S.W., Washington, D.C. 20460. To ensure your full protection under the emission warranty made applicable to your vehicle by Federal Law, and your right to participate in future recalls, it is recommended that you have your vehicle serviced as soon as possible. Failure to do so could legally be determined to be lack of proper maintenance of your vehicle. Also, your vehicle may fail a state or local emission inspection test if the recall work is not accomplished.

The enclosed postage paid owner reply card identifies your vehicle. Presentation of this card to your dealer will assist in making the necessary correction to your vehicle in the shortest possible time. If you have sold or traded your vehicle, please furnish us the complete name and address of the person you sold or traded your vehicle to and return the card to us.

IMPORTANT MESSAGE FOR CALIFORNIA RESIDENTS

The California Air Resources (CARB) requires that vehicle emission recall campaigns be completed prior to California registration renewal. Uncorrected emission recall campaigns will result in the inability to renew your California vehicle registration.

At the time of emission campaign completion, your California dealer will issue a "Campaign Certificate of Completion". Keep this certificate and, if required, present it to the Department of Motor Vehicles when renewing your California registration as proof of campaign completion.

We are sorry to cause you this inconvenience; however, we have taken this action in the interest of your continued satisfaction with our product.

GMC TRUCK DIVISION General Motors Corporation

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.