Decreased Engine Performance/Power, Filter Minder Indicator On, Possible MIL Illuminated and DTC P0101/P0103 Set (Replace AIr Cleaner/Reprogram ECM)

Some customers may comment on decreased engine performance/power on the above vehicles with the LB7 Duramax™ Diesel engine. The Malfunction Indicator Lamp (MIL) may be illuminated with DTC P0101/P0103 set. The customer may also note that the "filter minder" on the air cleaner assembly may indicate the filter element needs replacing at very low mileage. These symptoms are more likely to occur when pulling a trailer on wet/slushy roads, but have been reported in heavy rain, at curb weight, during highway driving.

The LB7 diesel engine creates very high air flow under load. The primary source of inlet air to the engine is through the right front fender. The tires kick up water spray on wet roads which is pulled in with the incoming air from the right fender opening located over the front bumper. This ingested water may soak the airfilter element causing increased restriction. This restriction may activate the "filter minder". If the water continues past the filter, wetting the mass air flow (MAF) sensor, the MIL may illuminate.

Important: If the vehicle is being driven through snowy and/or slushy roads that have been salted, the MAF sensor may be contaminated with soluble road salt.

Install a revised air cleaner assembly, P/N 25345138, that has a lower incoming air velocity. Also, seal off the right inner fender panel air inlet holes and reprogram the ECM by following the procedure below.

1. Open the hood and install fender covers.
2. Remove the air cleaner assembly hose clamp from the ductwork.
3. Disconnect the MAF sensor electrical connector.
4. Remove the air cleaner assembly from the vehicle by pulling upward.
5. Examine the air cleaner assembly for signs of salt intrusion (white, chalky powder). If signs of salt are present, and the vehicle has set a DTC P0101 or P0103, install the air cleaner assembly by reversing the three steps above. Refer to the Engine Controls sub-section of the 2001 Service Manual. The diagnostic table for DTC P0101 or DTC P0103 outlines the testing procedure for the MAF sensor. If the diagnostic test indicates a contaminated MAF sensor (out of range), remove the air cleaner again and discard the complete assembly. Otherwise, remove the air cleaner and continue with the next step.

Important: It is critical that the surface you will bond the mastic material to be clean and grease free. Poor preparation could lead to the mastic coming loose and being sucked against the air filter element causing a poor power condition.

6. Clean and degrease the right inner fender panel around the holes previously used for air intake.

Important: Depending on the exact size of the mastic material received and the fasteners on the inner fender panel, you may need to trim the mastic material to achieve a good fit.

7. Apply the mastic material to the inner fender panel, completely covering and sealing the two holes that the original air cleaner snorkels protruded into. Make sure that the mastic is firmly adhered to the inner fender panel.
8. Remove the two fasteners retaining the MAF sensor from the original air cleaner and transfer the MAF sensor to the replacement air cleaner. If the MAF sensor was judged to be contaminated in step 5, install a new MAF sensor, GM P/N 88892543, to the replacement air cleaner.
9. Position the new air cleaner to the mounting tray and firmly seat the push-in retainers.
10. Attach the air intake hose to the air cleaner assembly and secure the clamp.
11. Connect the MAF sensor harness to the sensor.
12. Recalibrate the ECM with the latest update. The calibrations are available from Techline starting September, 2001 on the TIS 2000 version TIS 10/2001 data update or later. Refer to the Tech 2 user guide for specific reprogramming instructions when using the scan tool.
13. Remove the fender covers and close the hood.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: