P0101 code after Fuel Filter change

Post by **Skymongrel** » 23 Jan 2020, 17:21

Hi all, first post but I've visited many times to troubleshoot. This has me stumped any help is appreciated.

2006 XC70 158K miles:
I replaced the fuel filter today with a Mahle KL196 took it for a drive and the check engine light came on. Autozone pulled the code and it was a MAF P0101.

The original filter was quite old... I never changed it maybe the PO did. Don't know. Has my fuel delivery been changed such that I'm getting this error? I've never cleaned the throttle body (looks involved), but have cleaned the MAF (last year).

Only other thing I touched was I removed bumper and installed a new windshield washer pump and fog lights. I tested my headlamp washers several times during my test drive. Could this almost atomized washer flow from the headlamp sprayer have made it to the air intake and altered a MAF calculation? I know this sounds stupid.

I did check the direction of the filter install. Looks ok. Took it for another test drive and no symptoms, rides and runs fine.

Thanks for any advice!
Scott

Post by **matthew1** » 23 Jan 2020, 17:57

If the only thing you changed was the filter -- anything that has anything to do with combustion -- and it's the right part (I didn't check) and in the correct configuration, I'd keep driving, keep clearing the code.

If the code returns after a say a hundred miles, then there's something.

Check MAF connections. Re-seat. Look for disturbed vacuum lines. I mean, more disturbed than they are in their natural state in turbo Volvos, which is very.

Post by **Skymongrel** » 23 Jan 2020, 20:01

Wow, thanks for quick reply. Appreciate it. Yes tomorrow I'll take another close look in the engine bay. I did relieve fuel pressure at the shrader valves before changing filter but other than the bumper removal and washer reservoir/pump nothing else.

It did throw a P0101 last winter. Just once during single digit temps. Cleared itself. Maybe it will do the same!

Post by **matthew1** » 23 Jan 2020, 20:09

Sometimes you can drive these problems away. How many miles have you put on since the filter change?

There is the outside chance the filter change disturbed some material in the line, causing it to move into a position that affects fuel/air mix, triggering the MAF code.

There is the remote outside chance that coincidence has simply struck down your MAF at the same time you changed the fuel filter. These double-variable situations are insidious, evil happenings caused by crossing a black cat's path, or similar.

There are several topics here on your code by the way.

Post by **abscate** » 24 Jan 2020, 07:42

You got some air in your line, and that has temporary messed up the trims/fuel pressure enough to code.

Definitely drive it for several drive cycles , or 500 miles

Next time I whip through ROC I can clear codes and read trims, too.

Post by **vtl** » 24 Jan 2020, 07:57

P0101 has nothing to do with fuel filter. No way on Earth fuel filter replacement may trigger any MAF errors. So, there's something going on with the MAF.

ECU on this engine relies on MAP, FPS and H2OS sensros for combustion. MAF is not a critical sensor, I once forgot to plug it back and had driven 200 miles without check engine light set or even symptoms.

Post by **Skymongrel** » 24 Jan 2020, 17:38

matthew1 wrote: ↑23 Jan 2020, 20:09 Sometimes you can drive these problems away. How many miles have you put on since the filter change?

Sure enough, today I drove it for about 15 miles and the code disappeared. Still seems to be running fine. I am gonna go through the engine bay to check MAF connectors and potential air flow issues. I've read many posts on this code and found numerous folks throwing a new MAF sensor at it to no avail. So I'm open minded about potential cause. Thanks again.

Post by **Skymongrel** » 24 Jan 2020, 17:45

abscate wrote: ↑24 Jan 2020, 07:42 You got some air in your line, and that has temporary messed up the trims/fuel pressure enough to code.

Air in the line seems quite plausible. Pull the filter and fuel drains out. I just didn't know if that would throw a code. I thought for sure that this common fuel filter change scenario would show up in the forum if it were also common for it to throw the P0101.

That being said...I drove fifteen miles or so today and the code just disappeared! Not celebrating yet. Wait and seen if it returns.
Thanks for offer to read trims. Expect I have a PCV and Throttle body cleaning in my future with 158k on the vehicle.

Post by **Skymongrel** » 24 Jan 2020, 18:00

vtl wrote: ↑24 Jan 2020, 07:57 P0101 has nothing to do with fuel filter. No way on Earth fuel filter replacement may trigger any MAF errors. So, there's something going on with the MAF.

Well your right. The code wasn't thrown right away after the fuel filter change and I didn't have problems starting after the change. I ran a short errand, two or three miles while testing the headlamp washers and then the code came right away. But I didn't dare start the thread by stating "Tested my headlamp washers and threw a P0101 code" ! lol

I have read in forum threads where a lot of MAF sensors have been thrown at P0101 without resolution of the code. So I didn't immediately what to go there (or spend the money yet). So to your point since I've seen this code once before, last year , (no fuel filter change there) I suspect your right. And although the code did disappear today after about fifteen miles of driving I'm gonna change MAF connectors and stuff. I do have a MAF cleaner and may give it a squirt. Thanks for advice.

Post by **Skymongrel** » 26 Nov 2021, 09:57

So I went to bring my XC70 in for an inspection. Last week I did all the brakes and changed the wiper blades to prepare for this. Started the car up and P0101 showed up....again! It been almost a year. And we have just had a cold snap, temps in the thirties.
I've read some threads on this code and will look for a vacuum leak somewhere. Someone suggested a cold weather related P0101 could be a manifold leak? Anyone with a similar experience out there?