07 Impala p0142

[Kevin D]

Hello Forum, this is my first post, here goes!

My flex fuel Impala lit the CELight, it's usually a loose gas cap but not this time. I used an Actron CP9580 to get the p0142 code "bank 1 rich". The "code connect" feature said something about the alcohol content of the fuel and I found a data point at 38% alcohol in fuel, rock solid no varying. That seems unusual to me since we use regular at 90-10 blend and not e85.

I used some spray cleaner on the MAF sensor and disconnected the battery for 1/2 hour. Afterwards, the light stayed out for a 10 mile drive but relit on a subsequent drive.

The car has not been refilled since the light came on.
Driveability is fine.
It is fitted with a K&N air filter.
70000 miles.

Did somebody fill the tank with e85?

Is this fuel parameter determined from a fuel sensor on my car or just programmed in, one size fits all?

[gmtech1]

I would run a tank of fuel from a different gas station. Also I have seen the oil from K&N filters coat the MAF sensors and cause issue rich conditions. You may consider cleaning the MAF and installing a OEM filter and see what happens.

Alcohol content should not be more than 10%, more than that will cause problems.

[Kevin D]

I refilled today from my usual station, did a 10 mile drive afterward, and the alcohol content is still showing 38%.
From my Actron scanner, the "Code Connect" top reported fix for p0142 is relearn alcohol sensor.
#2 reported fix is clean MAF sensor, so I'll have another try at that.

I'm just a beginner with this and I can't find a breath anywhere about how to relearn alcohol sensor. I think this is the thing I'm looking for, somewhere in the fuel line, but I'm guessing I need a more sophisticated device than my Actron to relearn it.
GM parts direct #12570260 $326 OUCH
Is this proprietary software territory?

[Kevin D]

I found this 3/2006 article at Autos.ca that describes a virtual flex fuel sensor V-FFS that relearns alcohol content when the car is filled.
I suppose all the other sensors must be working for this to be right.




http://http://www.autos.ca/auto-tech...x-fuel-system/

[gmtech1]

The fuel composition must be known before a relearn can be done. A special tool is required to test the amount of alcohol in the fuel. It must be below 15% before a reset can be done. After it is verified that the fuel is ok at the fuel rail, not the tank, the a scanner is needed to reset fuel trim and reset fuel composition. After this is done, the system will relearn the alcohol content.

[Kevin D]

gmtech1, thanks for your help.

I'm pretty sure I wont be doing any of this stuff. My scanner can reset codes, and offers lots of data, but reset fuel trim, reset fuel composition, I dont think so. The only other reset I know is disconnect the battery and maybe the settings will got to factory default, but that didnt happen when I tried it earlier. I'll be looking for an OEM air filter and recleaning the MAF sensor.

From the autos.ca article, I read that a fillup triggers the alcohol content relearn.

The Actron scanner offers lots of data but doesn't quantify any of it. So, I'm wondering what would a good, clean MAF sensor read at say 60mph? or conversely what would a dirty one read? I think the unit it displayed was LB/M, and the reading 3.48.

I may be losing it.... I scanned tonight and saw p0172 pending not p0142, oops

[gmtech1]

That's kinda what I figured, The info I posted is for the P0172 and the high alcohol content you are describing. On a E85 vehicle, a over-estimation of alcohol will result in a rich condition...