EPC Light & Fault Codes

  • Thread starter Deleted member 48395
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Deleted member 48395

Guest
I had had an intermittent problem with the EPC light coming on in my 1.6 16v. It only seems to happen at around 75mph but even then it isn't consistent. As soon as I turn the engine off and back on the light is cleared. Finally got it scanned today by any indy near me and had 2 fault codes:

16804 - Catalyst System; Bank 1: Efficiency below threshold
P0420 - 35-10 - - - Intermittent

17961 - Barometric / Manifold Pressure Signals: Implausible Correlation
P1553 - 35-10 - - - Intermittent

I was told I would need a new cat, new manifold pressure sensor and throttle housing cleaned (maybe replaced). Grand total £500 :censored:

I had new cat fitted in 2009 and this EPC light first came on in May 2011 (was a one off so didn't investigate further) so the cat would have been 2 years old! Even now I can't believe the new cat is knackered so was wondering what else it could be. I have done a few searches and seems that it could be the lambda(?) sensor that could be faulty? I had the cambelt done around May last year, also had a service shortly after which the aux belt tensioner snapped and was replaced. Is it possible one of these is linked to the problem (I also have a tapping noise from the engine bay, most noticable when cold).

Any thoughts would be much appreciated :)
 

Allan_84

Active Member
Apr 11, 2010
851
3
Denmark
look for exhaust leaks.
measure the lambda sensor with vagcom/vcds.
measure the map-sensor with vagcom/vcds.

if you can measure exhaust gases at a garage, cat is ok if:
O2 is = 0 or close to 0
CO2 is high, if i remeber it right, it should be like 14%

what the cat do:
CO + CO + O2 = CO2 + CO2
 
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Deleted member 48395

Guest
Cheers, sounds like I need to get it to another garage as I don't have VAGCom. Any tests/checks I can do at home? I noticed one thing last night when revving and fiddling to see if anything seemed odd. Given a quick tap on the throttle there is a sharp intake of air (sounds like someone wincing through their teeth) before the revs rise. This might be totally normal (I know nothing about cars :() but I don't ever recall hearing it before, but doesn't mean it wasn't there!
 

Deleted member 48395

Guest
I have now bought a fault code reader so I will clear the codes before I leave work and see if I can recreate the issue over the weekend while on the motorway (which is where the EPC light nearly always comes on).

If I can get the code(s) to appear again I guess my next step is to get the TB off and cleaned and then reset with VAGCom, clear the codes and try again!
 

Deleted member 48395

Guest
Having cleared the codes and done 400 miles over the weekend I only managed to trigger the EPC light once. The only code was 17961 - Barometric / Manifold Pressure Signals: Implausible Correlation, has anyone get any ideas on this one?
 

Deleted member 48395

Guest
Not had time to do anything really yet, but I now have VCDS and have been running a few checks to see what else I can check, another prime culprit seems to be the EGR Valve so will check that at the same time as the throttle body.

My car has a DBW throttle and yet the butterfly won't open when I put foot on the accelerator with the ignition on. This isn't normal is it?
 

Deleted member 48395

Guest
So I finally got around to cleaning the TB over the weekend. It was much worse than I expected!

Before:
imag0124cx.jpg

imag0123e.jpg


After:
imag0131u.jpg

imag0130yg.jpg


So far the car is running better, the hesitation at low revs is gone and seems a bit more responsive. The error codes haven't returned (yet) but I guess I will see over the coming weeks.

I did notice some other problems while I was working on the car.

The bit where the TB is boilted in (Manifold?) was really bad, worse than the TB. Should I worry about cleaning this and if so how would I go about it?
imag0129d.jpg


There was Mayo in the breather pipe (1st pic) and in the pipe in the engine cover along with oil on the air filter:
imag0137no.jpg

imag0128i.jpg

imag0133t.jpg


I cleared this out the engine cover pipe, but haven't done the breather yet, can I just remove and clean? is this something I should be concerned about.
 

Deleted member 48395

Guest
Now with EML Light

[:@] Thought this was fixed [:@]

EML light came on on Sunday, I hve cleared the code, but in the meantime while I wait for it to come back I was going to try and figure out what the hell is going on.

Before the light came on again I had done:
TB has been cleaned and reset
Had a fast idle test done at a garage and all readings were normal (see this thread)

Anyone have any ideas? I would have thought that this is pointing to a knackered lambda sensor as if there was a leak,surely this would have skewed the idle tests and such?
 
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getafix

Guest
Hi,

I am having the same issue's.
Basically, I have done everything you have bar the CAT replacement but I have replaced the CAT monitoring O2 sensor. no change.

Have you managed to sort your issue out yet?
 

Deleted member 48395

Guest
Hi,

I am having the same issue's.
Basically, I have done everything you have bar the CAT replacement but I have replaced the CAT monitoring O2 sensor. no change.

Have you managed to sort your issue out yet?

This issues seemed to go away after a few days and were fine ever since. I sold the car 6 months ago.
 
Lecatona HPFP (High-pressure Fuel Pump Upgrades)