Australian VW Polo 2003 EPC light problem

[Des Richards]

The light comes on when accelerating away from low speeds and from accelerating from a constant steady speed. Sometimes it will go into limp mode at the same time.

I’ve read the ECU with VAG.com and after much searching online and many hours looking under the bonnet for possible reasons and find nothing, I think that maybe I should ask for some other input.

Here are the results of the ECU. I am wondering what you guys would suggest for possible fixes?

Chassis Type: 9N - VW Polo
Scan: 01 02 03 08 09 15 17 19 25 37 44 45 46 56 76
VIN: WVWZZZ9NZ4U009934 Mileage: 157470km/97847miles
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Address 01: Engine Labels: 036-906-034-APE.lbl

Part No: 036 906 034 FJ

Component: MARELLI 4MV 4830

Coding: 00071

Shop #: WSC 20065

VCID: 5FC79D38DD3DB6E078F

WVWZZZ9NZ4U009934 VWZ7Z0C8097164

3 Faults Found:

17961 - Barometric / Manifold Pressure Signals

P1553 - 35-10 - Implausible Correlation - Intermittent

17912 - Intake Air System

P1504 - 35-10 - Leak Detected - Intermittent

17550 - Load Calculation Cross Check

P1142 - 35-10 - Lower Limit Exceeded - Intermittent

Readiness: 0000 0101

[Col]

I'd would all of the inlet tract for leaks letting un-metered air in and also check any vacuum hoses and or plastic t pieces, elbows etc.

[Des Richards]

I've had similar response from my local VW dealer, they want to take the inlet manifold off to check the seals. No guarantee, just a big quote. Is there anyway to be sure about this without exploratory surgery? In my experience exploratory surgery leads to further complications! I've also had another Euro garage tell me that the throttle body needed replacement.

[Col]

Just read my 1st response and it makes no sense!

It should have read, "I would check....."

What engine is it? 1.2, 1.4 ?

[Des Richards]

OK thanks, that makes a little more sense. Engine is BBY 1.4l petrol.

[Des Richards]

After removing and disassembling inlet manifold, and removing EGR valve, I found no evidence of air leaks but did find large amounts of carbon build up in throttle body and adaptor plate to the point were the EGR port was blocked completely and the throttle body butterfly would have been partially blocked. cleaned all parts, reassembled and adapted TB and EGR. Tested all OK except now at steady speeds (60kmh) car is hesitating sharply (like as though accelerator pedal is being pushed up and down rapidly) No error codes have been generated on short runs so further testing is required.

After reading other forums I came across an article regarding oil filler cap being removed and causing EPC error. I checked mine and found the filler adaptor neck was damaged and loose so have removed it and just put the cap direct to the engine. Tested removal while engine running and found that cap is needed to be sealed or EPC light will be generated. So I am now thinking the air leak errors were being created by the oil filler extension neck leaking.