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GM EGR and P1406 code FYI

01-27-2004, 12:59 PM
This happened on my '97 GMC 5.7L, but I'm sure the info is good for lots of other applications.
If your SES or CES light came on and you pull a P1406 code from your PCM, try this before you pay a shop to fix it:
Remove your EGR valve and soak it in about an inch of good carbon cleaner. Dont submerge the whole thing, just the bottom part where the valve seats. Leave it overnight and clean it really good the next day with a pick and a brush. (a small screwdriver and an old toothbrush work just fine.)
Push open the valve and carfully clean any carbon built up around the valve and seat. The valve should move freely and NOT stick in the closed position. When the valve is dry, reinstall it and clear the codes.
It worked for me, and could save you a trip to the shop. Good Luck!

01-28-2004, 11:04 AM
There is also a calibration update per GM tech bulletin#76-65-04 that reduces the "sensitivity" of the EGR desired and actual positions.
This calibration update also covers some other driveability concerns and false codes.

04-03-2004, 06:08 AM
GMMerlin....seeing that you are knowledgable in the wonderful world of GM's maybe you can help me.

The last time I took my 95 blazer to Chevy (2002), they told me that I needed to get an update for my truck's computer system. And then told me that i would have to pay the $82 an hour to get it updated.

I believe at the time i went up there i had a minor problem for them to address, can't remember. But i was thinking that if they were to update my computer, all sorts of things would malfunction and go wrong with my truck. Needless to say, I didn't get the update. Not good for my budget....

Have you heard of this? Is the update beneficial? Would my truck possibly run better?

12-14-2008, 08:20 PM
the reason for updates is because something is already wrong with your vehicle. not it might not even be a drivablity problem, there are all kinds of things that need updates, everything from major engine problems with the computer to small things like your cd player doesnt eject everytime. I have done hundreds of upgrades to GM vehicles over the years, and it has never made the vehicle worse. I would ask what the update is? ECM? BCM? sometimes a problem might not even be something you've noticed or encountered. ask the dealer... they can find out whats in the update, and you can make a decision to do it or not.

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