My 406 is driving me crazy, need some help

[Ivan495]

2002 Peugeot 406 2.0 HDi 110.

1. How do I disable check engine light? After replacing MAF few months ago, it is constantly showing "Anti pollution fault" and check engine light is on. And it doesn't go away. Mechanic even reset it but after car turning off and on, same thing.

2. A month ago, old problem showed again. RPMs are oscillating. Mostly between 1800-2000 RPMs. You can notice jerking, especially when letting off the gas. And where is most noticable is when I steer left. On right turn it's all fine, but on left, car jerks, RPMs aren't stable. Even has the tendecy to loose gas response for a 2 seconds.

Can anyone help?

[Captain Jack]

1. How do I disable check engine light? After replacing MAF few months ago, it is constantly showing "Anti pollution fault" and check engine light is on. And it doesn't go away. Mechanic even reset it but after car turning off and on, same thing.

Why did you replace the MAF in the first place? If that's when the light started, I'd start with replacing the MAF again with another one.

2. A month ago, old problem showed again. RPMs are oscillating. Mostly between 1800-2000 RPMs. You can notice jerking, especially when letting off the gas. And where is most noticable is when I steer left. On right turn it's all fine, but on left, car jerks, RPMs aren't stable. Even has the tendecy to loose gas response for a 2 seconds.

Sounds like a split in the hose/pipe somehwere. 2000 RPM is around when the turbo kicks in, so the extra boost in the hose is likely escaping through a split. The lefty-righty issue may also be explained by a split hose. If it's a tiny split, then the engine tilting in one direction (i.e. when steering left) may again be exacerbating the split as opposed to it tilting in another direction (i.e. steering right).

I'd be surprised if it's the split hose that's causing the engine check light too, rather than the MAF...

[GingerMagic]

Some aftermarket sensors are a bit hit and miss, some are great whereas others are inferior.

If you still have the old MAF then plug that back in - the EML might not go out straight away mind.

You also mentioned the oscillating revs - there is a chance your throttle sensor needs a clean - it's easy to do and I'm sure YouTube will show a video.
This would also illuminate the EML if it's not working properly.
Could also be a worn engine mount allowing too much movement and pulling on the cable.

Try these first and let us know how you get on.

[GingerMagic]

Try these videos....

MAF sensor cleaning
https://youtu.be/fAQdQ3RJvGo?si=izwVXcp3tNYBWKxy
The tiny wire inside is very fragile, so go easy with the spray cleaner

Throttle sensor removal.
https://youtu.be/4fYHo7voyx0?si=S_l07rH1Q8cLyy0s
This is essentially just a metal spring/coil affair that gets grime inside, can be cleaned with carb cleaner if I remember correctly.