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Discussion Starter · #1 ·
After months of intermittent CEL's (insufficient/low EGR flow) I finally got tired of it and removed/cleaned the throttle body, EGR valve, and EGR tube. The throttle body and EGR valve didn't seem that bad, but the tube was kinda clogged up with deposits. I cleaned all the afore mentioned parts pretty diligently so as not to have to do it again any time soon.

Well, a couple weeks went by without a CEL until one popped up again. This time it was the fuel sending (voltage) code. I knew it was on its way out and had the part on hand for months, so I went ahead and changed it out. Light off again. I figured "Great, no more CEL's" since these are the only two I've ever gotten.

Well, yesterday (about a month since I cleaned EGR tube, etc.) another CEL pops on.....insufficient EGR flow. Could some small flakes of carbon left behind still be in there causing the code to trigger again already. Surely it couldn't have gotten clogged back up again that quickly, right? I know I cleaned it pretty good and I'm not sure what direction to go next.

Should I remove everything and clean it again? Any other culprits that could trigger this code? If my flow is insufficient, what can I do to improve it other than what I already have?

Thanks.
 

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The ECM tests the EGR system by commanding the EGR valve open during deceleration and monitoring the MAP sensor for an expected change in manifold vacuum. The MAP sensor may be dirty preventing it from properly measuring manifold vacuum. The ECM thinks it is inadequate EGR flow P0401.
 

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So, do I need a new MAP sensor or can it be cleaned? I see they're about $50. Really tired of going to auto zone to have the code checked/erased
 

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Buster28 said:
The MAP sensor can be removed and cleaned. It has a sensing port that extends down into the manifold that can get blocked up with carbon.

This link provides technical data on the sensor : http://www.autosensor.com.cn/611/index.htm The Isuzu part # is 8-16212-460-0

This link shows a typical dirty sensor (Jeep) : http://liberty.eurekaboy.com/mapsensor.htm
Thanks for the info, I'll try cleaning it when I have time. Will carb cleaner be ok, or is there actually MAP cleaners?

Also, I read in another thread that intermittent CEL's can be triggered by a faulty ECM ground. Any thoughts on this?
 
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