Repeated code

DAN BALLARD

MEMBER
2004 CHEVROLET COLORADO
4 CYL
2WD
AUTOMATIC
227,000 MILES

I have the truck listed above and it is missing off and on, accelerator coming and going. Repeatedly showing engine code for "too lean and" and "Upstream o2 sensor". I've replaced the accelerator pedal assembly, the o2 sensor, the MAP sensor and the air volume sensor. What gives?

4 Replies

JOETECHPRO

MECHANIC
705 POSTS

Hey Dan Ballard,

I would say the first check given that you have a lean condition code is to check for vacuum leaks. Guide below:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

After that i would advise checking the fuel pressure to ensure it is not low.
Replacing the fuel filter if it has not been done is a good idea, you can then check the old filter for excessive debris, this gives you an indication of the contents of the tank.

Do you have access to a scanner with live data?

If so can you check the long term fuel trims
Also can you let me know what you have for short term fuel trims at idle and then with the engine revs raised to 2,500 rpm?

Regards, Joe

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Wednesday, April 10th, 2019 AT 7:42 AM

DAN BALLARD

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3 POSTS

Thanks for replying so promptly. I will work on what you recommended today and get back to you tonight or tomorrow. Thanks, Dan

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Wednesday, April 10th, 2019 AT 8:04 AM

DAN BALLARD

MEMBER
3 POSTS

Joe, It was apparently the fuel filter and the wrong MAP sensor combined. I replaced them both yesterday and all looks well. Thanks again for your help. Dan Ballard

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Thursday, April 11th, 2019 AT 7:10 AM

JOETECHPRO

MECHANIC
705 POSTS

Hey DAN BALLARD,

No problem, glad to help.

Thank you for letting us know the fix you found, the information provides a reference for others with the same issue.

Best of luck, if you have any further problems let us know.

Regards, Joe

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Sunday, April 14th, 2019 AT 7:32 AM