CEL extinguishes on its own after repair, then relights shortly thereafter

[3Aone]

Hey BITOG, I always get some good insight from you guys.

Situation: I get a P1101 in my 19 Equinox. take it to the shop I've had good experiences with before, shop manager says bad MAF sensor. They replace it and test drive it, the CEL extinguished itself during the drive. That's good, right?

I go to pick it up and start/stop a couple times in the parking lot, and the CEL re illuminates! They try another MAF, no good. Now they say they're gonna try a new MAP and cleaning the throttle body.

I have a hunch the light initially going off tells us something, any ideas?

 

[Rand]

Do you have any mice around? Might be wiring damage. (rodent or not rodent related)

Can you look at live data?

 

[3Aone]

I thought maybe that, wiring. The mechanic can determine this with a multimeter, right? or maybe I'll have to do it myself.

Live data, no, but the shop can, should've, right?

I can understand a misdiagnosis but my confidence in their approach after the fact could be better.

 

[Jethro_Bob]

Are you absolutely sure it was an all new MAF? They should not be rebuilt but many remanufacture try.

 

[Danno]

Are you absolutely sure it was an all new MAF? They should not be rebuilt but many remanufacture try.

Or a Dorman, where OE is the correct choice.

 

[3Aone]

Or a Dorman, where OE is the correct choice.

Aftermarket I believe, with at least one being a Hitachi.

 

[Nukeman7]

Could be damaged wiring or possibly an air leak from a crack in the rubber bellows boot. I'd take a flashlight and inspect both areas closely.

 

[Trav]

Aftermarket I believe, with at least one being a Hitachi.

You may be a victim on bad parts. MAF and other sensors should really be replaced with OE parts, I have seen many junk sensors that were brand name aftermarket or remans, I had 2 MAF fail in minutes after install, they should easily be able to see what it is doing.

 

[3Aone]

You may be a victim on bad parts. MAF and other sensors should really be replaced with OE parts, I have seen many junk sensors that were brand name aftermarket or remans, I had 2 MAF fail in minutes after install, they should easily be able to see what it is doing.

I think you two talking about oem might be onto something. another thing I noticed- you can clear the CEL, drive several miles, start and stop many times, put in gas, but as soon as you cold start (like ten minutes off) the CEL is on almost instantly. Could this mean basically the car doesn't like the MAF from the get go, seeing it's hardly being given a chance to function?

 

[eljefino]

Whatever the computer uses to validate the MAF sensor will be other sensors... oxygen, MAP, TPS. If the fuel trims drifted under the old MAF drifting out of calibration, your computer can be comparing the new MAF to the last "barely good" data. A battery disconnect and reset should reset everything, which you didn't do.

But this is theoretical; it's way more likely there's something in the MAF "chain" to include the air intake tube, vacuum leaks, wiring, defective new parts.

 

[3Aone]

Whatever the computer uses to validate the MAF sensor will be other sensors... oxygen, MAP, TPS. If the fuel trims drifted under the old MAF drifting out of calibration, your computer can be comparing the new MAF to the last "barely good" data. A battery disconnect and reset should reset everything, which you didn't do.

But this is theoretical; it's way more likely there's something in the MAF "chain" to include the air intake tube, vacuum leaks, wiring, defective new parts.

Got it. I'll give it a try. I relied on the shop!

 

[clinebarger]

P1101 doesn't necessarily mean the MAF sensor is/was faulty, The diagnostic trouble tree is quite extensive.

The first thing it has you do is check the Throttle Body Idle Air Flow Compensation percentage....If above 90%...Clean the throttle body.

Ask for the original MAF sensor back while they clean the throttle body, If the code comes back...Take it to a Diagnostic Tech/Mechanic.

Many Mechanics cannot diagnose Engine management/Performance issues but be proficient at other tasks like Brakes, Steering/Suspension, & Component R&R.

 

[3Aone]

UPDATE: It was the throttle body alright. Cleaning it would've been appropriate, but for the fact replacing it was appropriate.