Recently, my SES light came on because of the MAF in the intake tube saying it was detecting moisture. The service at my dealer said there is an update for the 2001 models because of this. I'm sure there's more to it than just the MAF sensor issue. I believe I read that a few people had some updates done to their computer and weren't as satisfied with it as before the update. Can you shed some light on this update for the 2001 models?

<H1>Decreased Engine Performance/Power, Filter Minder Indicator On, Possible MIL Illuminated and DTC P0101/P0103 Set (Replace AIr Cleaner/Reprogram ECM) #01-06-04-050 - (Oct 19, 2001)</H1></TABLE>Decreased Engine Performance/Power, Filter Minder Indicator On, Possible MIL Illuminated and DTC P0101/P0103 Set (Replace Air Cleaner/Reprogram ECM)


2001 Chevrolet and GMC C/K Pickup Models


with 6.6L Duramax™ Diesel Engine (VIN 1 -- RPO LB7)<A name=ss1-826937><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=826937&amp;psdid=210&amp;evc=sm#ss1-826937" target="_blank">
<H5>Condition</A></H5>


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.<A name=ss2-826937><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=826937&amp;psdid=210&amp;evc=sm#ss2-826937" target="_blank">
<H5>Cause</A></H5>


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.



<H4>Important</H4>


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.


<A name=ss3-826937><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=826937&amp;psdid=210&amp;evc=sm#ss3-826937" target="_blank">
<H5>Correction</A></H5>


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.
[list=1]
<LI =1>Open the hood and install fender covers.
<LI =1>Remove the air cleaner assembly hose clamp from the ductwork.
<LI =1>Disconnect the MAF sensor electrical connector.
<LI =1>Remove the air cleaner assembly from the vehicle by pulling upward.
<LI =1>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.



<H4>Important</H4>


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.



<LI =1>Clean and degrease the right inner fender panel around the holes previously used for air intake.



<H4>Important</H4>


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.



<LI =1>Apply the mastic material to the inner fender panel, completely covering and sealing the two holes that the origin

Thanks for the info. I never drove in any rain when this happened. This occurred a couple of days after I cleaned the filter on my K&amp;N intake, which involves de-oiling, cycling water through the filter, and then applying the new oil. I may have not let it dry long enough. I'll clear the code with the Bullydog Powerpup and see if it comes on again. If it does, I'll replace the MAF. If it STILL comes on, I'll install my new Volant intake. Right now it runs as strong as it ever did, and the SES light is still on. Only one more question. Is the computer in our trucks designed to make the SES light go out when corrected conditions are met, or will it stay on forever until you clear that particular code?

K&amp;N oil can get sucked in and contaminate the MAF sensor. You can try cleaning the MAF by bathing it in denatured alcohol. Let it air dry. The codes will clear if the sensor tests pass enough times.

They replaced the MAF.