GT TDi Not Starting CBAB

[suomy]

Hi There
I have a 2009 GT TDI 2.0 with the CBAB engine. It would have a very intermitant fault where it would turn over on the starter and not fire. After 2 or 3 tries it would start straight away and run fine. However this weekend its just decided not to start at all. The fault codes flagged up are unrelated to the engine but they're the same ones each time. They would erase and only come up on a non start - this time however they're not erasing

It has the symptoms of a crank sensor but no fault codes suggesting so. I have seen threads where people have had similar issues, changed the crank and cam sensors and it made no difference but no one seems to of reported back if they got it sorted and what the fault was.

So I was wondering if anyone has had the same issue and had it resolved? If so what was the fix?

Many thanks in advance. This has been quite a head scratcher

[philipharmes]

Would be usefull if you said what the fault codes were.

I take it that the engine is actually turning over but not fireing.

Have you tried a squirt of easy start or brake cleaner in the inlet to see oif it will fire.

A common problem is the throttle valve getting stuck shut due to gung from the EGR.

[suomy]

Would be usefull if you said what the fault codes were.

I take it that the engine is actually turning over but not fireing.

Have you tried a squirt of easy start or brake cleaner in the inlet to see oif it will fire.

A common problem is the throttle valve getting stuck shut due to gung from the EGR.

Yes the engine is turning over but just not firing. The mk5 Golf had a low crank speed sensor where if it was less than 270 RPM or something it wouldnt allow the engine to fire. I didnt know if the mk6 had the same system?

I only a have list with the system name and status. These are

Brakes = Fault
HVAC = Fault
Central electrics = Fault
Dash Board = Fault
Gateway = Fault
Steering Assistance = Fault

I will investigate the gunged throttle valve - now you mentioned it I vaguely remember hearing it before

Thanks for your reply

[Keithuk]

I only a have list with the system name and status. These are

Brakes = Fault
HVAC = Fault
Central electrics = Fault
Dash Board = Fault
Gateway = Fault
Steering Assistance = Fault

I will investigate the gunged throttle valve - now you mentioned it I vaguely remember hearing it before

Those aren't error codes?

You need to get your motor scanned (preferably with VAG-COM\VCDS) for any error codes logged in the ecu and post them, that will save a lot of guessing and check systems out.

[Crasher]

The throttle valve has a feedback position sensor so a proper code read will tell you if it is stuck and when they are closed the engine turns over faster as if it has no compression... as it doesn’t.

[suomy]

Just a heads in case anyone else has a similar issue as it has now been resolved.

I was able to turn the engine over without depressing the clutch pedal making me think it could of been the clutch pedal switch. Not the case. It turned out to be a faulty relay casuing a voltage drop which prevented sufficient communication between the ECU and other systems hence the random unrelated fault codes. New relay fitted and the car now starts first time every time and no more fault codes