'How to Fix' - Manifold Pressure Sensor fault

[Sarge786]

Hi Guys my first 'how to' here, hope it helps someone.

I found that the engine light came on and after the engine was run for a few mins, it would either start 'hunting' (revs bouncing up & down) or turn off, this is after the autochoke went off, this would then cause a little difficulty restarting.

I did a Vag Com scan and found:
1 fault found:
17566 - Manifold Pressure Sensor (G71): Implausible signal
P1158 - 35-10 - - - Intermittent
Readiness: 1010 0101

SO I had a look around at the sensor and wiring, it all seemed to be ok, so unable to test the sensor without changing it, and not having a spare, I decided to do basic checks, (it's funny how people jump to conclusions, spend cash, then find afterwards that they should have checked basics first).

Having a look around and feeling the full length of the pipe that the sensor is fixed in, I discovered that this pipe had been rubbing against the brake pipe next to it, and it had gone through (out of sight) causing a hole in the pipe!.

SO, to remedy this, I cleaned up the pipe and used good old self Amalgamating tape (every tool box should have this, it's very useful) around the hole in the pipe, creating an air/water tight seal. Don't be tempted to use insulation tape as this usually undoes it self after a little bit of heat, and is pretty useless in greasy situations. I then cleared the fault code using Vag Com, and Valla!.. idling normal, and no fault found!..


;)
SARGE

[pgodoe]

Thanks, this might fix my problem as well.

I have the fault code: 17559 - Long Term Fuel Trim Additive Air Bank 1: Range 1: System too Lean
P1151 - 35-00 - -

I did'nt quite understand what kind of pipe you where talking about. The only trouble I had when I tried to clean the MAP-sensor was getting around the gear oil measuring device (?).
My car symptoms are trouble starting when engine is medium warm (something about the autochoke not adjusting maybe?) and unstable revs.

-P- :)

[Sarge786]

I was gonna take a picture of the pipe but, found that my mate took my digi camera over bank holiday, The pipe is the the one with the actual sensor in it, if you look/feel lower down it 'passes' next to what I think is the metal brake pipe, this is where the damage was on mine. I will put a pic up when I get my camera back for you.

SARGE

[Chris Steele]

Hi Sarge,

I too have had the manifold pressure error and experienced the same problems. Mine went into a low power setting to just about get me home. Got RAC out and they found fault 17961 altitude/intake manifold pressure signal implausible ratio. They reset the throttle settings and all was fine until a month later when the Engine Management Light came on and it's stayed on ever since (last two months). Took it to the local Audi dealer for them to check all the vacuum hoses and they diagnosed a faulty MAP sensor - £400 odd quid for a new one !! As the car has just had £400 spent on it for a new cam belt and water pump I have decided to live with it as there are no symptoms. I would be interested to see the photo when you are able to take one.

Chris

Audi A2 1.4 Petrol December 2000 (X)

[pgodoe]

I was gonna take a picture of the pipe but, found that my mate took my digi camera over bank holiday, The pipe is the the one with the actual sensor in it, if you look/feel lower down it 'passes' next to what I think is the metal brake pipe, this is where the damage was on mine. I will put a pic up when I get my camera back for you.

SARGE

Thanks, Looking forward to see where it could be!

[Sarge786]

Hi, For you guys, I ran over to a another friend today (any excuse to drive Shoby car at moment :)) and used his camera to take a few pics for you, as my git of a friend hasn't returned mine as yet :)

It is a little hard to see because of everything in the way, but compare it to your engine bay and you will see.

Remember this is a Petrol 1.4i SE model..

One thing to note, in my personal opinion, it is too often that the dealers scan the car and point out to a 'sensor' fault, charge you the earth to simply change it. The sensor is there to TELL you that there is a fault/issue, and while noted, that occasionally the sensor itself becomes faulty, dealers will only too happily tend to replace the sensor and clear the fault with their equipment. IF the sensor was not at fault, this maybe ok for a few days or even a few months but may not be the correct 'fix', because lets say a dealer moves things around (pipes wiring etc)while changing the sensor, he may have twisted the pipe (say in my case) and caused the tiny hole in the pipe to become sealed temporarily, then skinned me alive with his charges, but sooner or later it would have re-appeared, then what? will he refund it all to you?

I mean if a car oil light comes on, your not going to change the sensor at first are you?, your going to see if it actually needs oil or if theres a leak, and why it is so.

Moral of my story, (I hope I'm not offending anyones mechanical/technical abilities on the forum) but, ALWAYS do your own checks very carefully, before submitting to the wrath of the dealerships. You may save ££££'s (proberbly will, and you know the jobs a good one, after all no one looks after your baby quite like you do!) ;)

Anyway here's some pics. If anyone has a engine bay diagram, I would be able to point it out on there for you.

Hope it helps. :cool:


Regards
SARGE

[pgodoe]

great stuff man! I'll have a look tomorrow!

[pgodoe]

Hi, For you guys, I ran over to a another friend today (any excuse to drive Shoby car at moment :)) and used his camera to take a few pics for you, as my git of a friend hasn't returned mine as yet :)

It is a little hard to see because of everything in the way, but compare it to your engine bay and you will see.

Remember this is a Petrol 1.4i SE model..

One thing to note, in my personal opinion, it is too often that the dealers scan the car and point out to a 'sensor' fault, charge you the earth to simply change it. The sensor is there to TELL you that there is a fault/issue, and while noted, that occasionally the sensor itself becomes faulty, dealers will only too happily tend to replace the sensor and clear the fault with their equipment. IF the sensor was not at fault, this maybe ok for a few days or even a few months but may not be the correct 'fix', because lets say a dealer moves things around (pipes wiring etc)while changing the sensor, he may have twisted the pipe (say in my case) and caused the tiny hole in the pipe to become sealed temporarily, then skinned me alive with his charges, but sooner or later it would have re-appeared, then what? will he refund it all to you?

I mean if a car oil light comes on, your not going to change the sensor at first are you?, your going to see if it actually needs oil or if theres a leak, and why it is so.

Moral of my story, (I hope I'm not offending anyones mechanical/technical abilities on the forum) but, ALWAYS do your own checks very carefully, before submitting to the wrath of the dealerships. You may save ££££'s (proberbly will, and you know the jobs a good one, after all no one looks after your baby quite like you do!) ;)

Anyway here's some pics. If anyone has a engine bay diagram, I would be able to point it out on there for you.

Hope it helps. :cool:


Regards
SARGE

If what you are referring to in the picture as a "sensor" is actualley the MAP-sensor I have been looking at the wrong sensor!!:eek:

I thought what is called the "intake manifold pressure sender" was the MAP-sensor. Hmm..

I had a feel at the vacuum hose, and it was thin because of the brake pipe as you sad:) But i could not feel a hole all the way trough. I will get some tape just i case.

Thanks, I think you just saved me a lot of money:)

Regards,

-P-

[Chris Steele]

Cheers for the photos. This is where I had been looking. I too can't feel a hole in the pipe but can see that the brake pipe has been rubbing against it. I will get some of that self-amalgamating tape you mentioned and see what happens.

Thanks again !!

Chris

[Sarge786]

Your welcome guys! ... more to come as soon as I can find something to do on car ...LOL ;)




Cheers
SARGE :D