VW Fox 1.2 3 cylinder P0342 error

VW Fox 1.2 3 cylinder P0342 error

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Wing Commander

Original Poster:

2,179 posts

231 months

Sunday 11th August 2013
quotequote all
Hi all

A family member has a 2007 VW Fox with a 1.2 3 pot engine. Occasionally an engine light comes up which, when I read it with my code reader, displays P0342. Previously, the car came up with P0341.

After the first code (P0341) I changed the cam sensor and this appeared to fix things, although the owner of the car is about as un-PH as possible, so when I asked if it felt better than before, I got a blank face looking back at me.

Anyway, now the car has come up with this light and P0342. She took it to a local VAG specialist who has said (and I am only going on what the family member has relayed to me) that this is a really common problem on the VW Fox and the car needs a new ECU.

Anybody care to shed some light on this matter based on this sketchy information?!

Thanks in advance!

bearman68

4,642 posts

131 months

Sunday 11th August 2013
quotequote all
Can't tell. The codes you mention are cam sensor related. However, you need to check to see if the ecu is reading the cam sensor signal (ie is the signal getting to the ecu via the wiring, and is the signal correct). Your VAG specialist should be able to do this with a scope. If they don't they are only guessing.
If the signal is getting to the ecu then it could be in trouble, but check first, as ecu failure is a rare thing IME

Wing Commander

Original Poster:

2,179 posts

231 months

Sunday 11th August 2013
quotequote all
bearman68 said:
Can't tell. The codes you mention are cam sensor related. However, you need to check to see if the ecu is reading the cam sensor signal (ie is the signal getting to the ecu via the wiring, and is the signal correct). Your VAG specialist should be able to do this with a scope. If they don't they are only guessing.
If the signal is getting to the ecu then it could be in trouble, but check first, as ecu failure is a rare thing IME
Thanks for the thoughts. I think I shall call the garage tomorrow and see what they have to say first hand. Hopefully I can glean a bit more info and progress from there

Thanks again

shoehorn

686 posts

142 months

Tuesday 13th August 2013
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I replaced the ecu on a 3 cyl 2006 polo which started with an intermittent eml coming on,this developed into a lowish rpm stutter,which ended in non starting showing a cnk sensor fault.
On cranking live data showed no engine speed signal.
We checked the signal at the ecu pin and were in fact getting a signal and after a discussion with a random independent VW specialist who had replaced a couple himself the ecu was replaced,which cured it.
I would guess that the component that deals with cnk signals also deals with cmp signals and is effectively ste.
If the wiring is good and you have fitted a new(genuine?)sensor then it only really leaves either an air-gap fault(highly unlikely)an ecu fault or the timing has jumped a tooth or 2 which is not unknown in those engines.

Wing Commander

Original Poster:

2,179 posts

231 months

Thursday 15th August 2013
quotequote all
shoehorn said:
I replaced the ecu on a 3 cyl 2006 polo which started with an intermittent eml coming on,this developed into a lowish rpm stutter,which ended in non starting showing a cnk sensor fault.
On cranking live data showed no engine speed signal.
We checked the signal at the ecu pin and were in fact getting a signal and after a discussion with a random independent VW specialist who had replaced a couple himself the ecu was replaced,which cured it.
I would guess that the component that deals with cnk signals also deals with cmp signals and is effectively ste.
If the wiring is good and you have fitted a new(genuine?)sensor then it only really leaves either an air-gap fault(highly unlikely)an ecu fault or the timing has jumped a tooth or 2 which is not unknown in those engines.
Thanks for the input - sorry for my reply in getting back to you.

I have left it with the family member to get a second opinion as it sounds feasible it could be the ECU. I am always wary when a female goes to a new (to them) garage and they quote big bucks to fix a problem without really explaining things.

I will await the second opinion and take it from there. Thanks again to both of you

wettrackday

30 posts

169 months

Friday 23rd August 2013
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I have done several timing chains on these I believe it's a common problem as they stretch. Hope this helps.