P0234 - Limp Mode + Flashing Glow Plug Light + CEL?

I was accelerating in third gear (manual car...if that matters) when the car just stopped accelerating. I was like "W T F?"...looked at the dash...and was greeted with a flashing glow plug light. The car wouldn't go above ~1,700 RPM (it got there SLOWLY) and wouldn't go above about 45 MPH.

Edit: As I mentioned below...I managed to meet up with a great/helpful forum member and was at least able to get the code pulled. Any idea what might be causing P0234? It looks like some possibilities are stuck turbo vanes or faulty N75.

Do you get a blow off sound after 2k rpm under load. Had the same problem. Happened to my q7. I would restart and light would go away but as soon as I would hit around 2k it would come back. Mine was a hose clamp came off and the line not being connected would create an under boost condition.

It doesn't sound like a blow off or diverter valve under load. The sound of the factory air box is fairly pronounced under load though. Almost as loud (air rush/intake) as the Eurosport Cool-Flow intake I had on my old 1.8T.

I don't know if it's related or not...but there's an occasional whining sound under the hood (like a pump or something or other kicking on or off).

A forum member was good enough to meet up and help me out late this afternoon.

The lucky winner is P0234 "Boost Pressure Regulation." Thoughts?

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Address 01: Engine (CJA) Labels: 03L-906-022-CBE.clb
Part No SW: 03L 906 019 HE HW: 03L 907 309 AA
Component: R4 2,0L EDC G000SG 8174
Revision: 12H15--- Serial number:
Coding: 0050072
Shop #: WSC 00066 000 00000
VCID: 75E1EE161C971EEA81-8020

2 Faults Found:
000564 - Boost Pressure Regulation
P0234 - 000 - Limit Exceeded (Overboost Condition) - MIL ON
Freeze Frame:
Fault Status: 11100000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 88135 km
Time Indication: 0
Date: 2016.08.04
Time: 06:32:00

Freeze Frame:
RPM: 3289 /min
Speed: 54.0 km/h
Load: 98.4 %
Pressure: 2347.4 mbar
Pressure: 2843.5 mbar
Lambda: 0.8 %
Lambda: 51.3 %

000564 - Boost Pressure Regulation
P0234 - 001 - Limit Exceeded (Overboost Condition) - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 88135 km
Time Indication: 0
Date: 2016.08.04
Time: 06:32:00

Freeze Frame:
RPM: 3289 /min
Speed: 54.0 km/h
Load: 98.4 %
Pressure: 2347.4 mbar
Pressure: 2843.5 mbar
Lambda: 0.8 %
Lambda: 51.3 %

Readiness: 1 1 0 0 0

Could be a problem with the actuator. Maybe the vacuum line popped off or is leaking. I'd clear the codes and try giving the car some vigorous exercise. Maybe find a long steep grade you can power up in third/fourth gear. That should help clear the turbo vanes if they are sticking.

That's the problem...If it's a turbo vane issues...it's because of the amount of time the car has spent in stop and go traffic. I would have thought that me getting on it otherwise would have offset that issue.

I don't abuse it...but I am far from easy on it. Since early on...it's received a good amount of spirited acceleration/driving, with the exception of sitting in traffic time.

Would some sort of fuel infejection cleaner (I've never added anything) do anything for it on the way out (exhaust side) or is it too late for that?

I will check for a vacuum leak as you suggested. Hopefully it's something that simple. Thank you for your response.

I wouldn't bother with the fuel injector cleaner. The actuators do go bad occasionally. The dealer will just replace the entire turbo assembly rather than replace a faulty actuator. Your description of a whistling/whining sound makes me think you could just have a vacuum leak in the actuator circuit.

turbobrick240 said:

I wouldn't bother with the fuel injector cleaner. The actuators do go bad occasionally. The dealer will just replace the entire turbo assembly rather than replace a faulty actuator. Your description of a whistling/whining sound makes me think you could just have a vacuum leak in the actuator circuit.

Click to expand...

I'm hoping that I can fix it myself (if it's a minor issue). I will write down all of the suggestions here and attempt to troubleshoot what I can before I resort to taking it to the dealer.

After calling several dealers and VW Customer Care yesterday (attempting to get an appointment and a loaner vehicle)...I was given the impression that they aren't particularly interested in covering this. They specifically referenced what they called the "engine and transmission" warranty...not the "powertrain" warranty. I did not take that as a promising sign that they're going to just pick up the tab for an issue that is other than "engine" or "transmission."

I'm going to cross my fingers, but this might explain the issue. I went and looked around under the hood and found exactly what was in the link below (MK V TDI shown, but same concept).

When the air filter was changed last (I think at the 40k service)...it appears that they did not properly secure the vacuum hoses. Both the larger one with the two big rubber guards and a smaller one were not secured. This can apparently lead to pinching in the hose...and not permitting the N75 to discharge line pressure (overboost when boost should be near zero when not under load).

I'll see if I can get the code reset to test this theory.


http://kansascitytdi.com/06-jetta-overboost/

So pretty much either the hose issue, faulty N75, or the turbo needs to be replace (stuck vanes). At least that's how it's looking.

Edit: The code won't reset with a regular OBD II scanner. Oh well. I'll take it lengthy drive tomorrow and see if it will go into limp mode again.

Edit 2: The code reset itself this morning. There were no lights on when I started the car this morning. I put 120+ miles on it today. No lights or limp mode. Another thing...I did not hear the grunt/groan sound from the engine bay a single time today (including time in traffic...I was in the car with the engine running for 4+ hours). I wonder if that sound was the pressure attempting to vent from one of those hoses? Anyways...the troubleshooting step of checking the vacuum lines first saved me the PITA of having to deal with the dealership. Thank you.

I have a 2010 Jetta TDI 6MT and got the flashing glow plug light plus limp mode this afternoon for the first time. The car only has 55,000 miles. I turned it off, turned it back on the light was gone so I drove it for about 10 miles and it drove normally. I then let it sit for about 2 hours and when I turned it on again, the flashing glow plug light is back and I'm stuck in limp mode. The VW dealers are closed for the day and closed on Sundays and I'd prefer not to be late for work on Monday, but can be if I have to. Any thoughts as to the issue and / or solutions? I plan to let VW buy back this car, but would like to wait until the end of the buy back period in 2018, but also do not want to spend a lot of money now on an expensive fix. Thoughts?

Check out the post just before yours. I secured the vacuum lines and I haven't had an issue since (knock on wood).

Pop the hood. Ensure that the vaccum lines are all properly secured in their clamps. I'm not saying that's your issue, but it was that easy for me. "Fixed" it in about five seconds.

Had same problem glow plug light flashing and loos of power

Took my 14 tdi to the dealer paid for diagnosis and the mechanic at the dealer said it was a pinched vacuum hose from when whoever took the airbox off last time which was them but that’s what it was if this helps anyone out

turbobrick240 said:

Could be a problem with the actuator. Maybe the vacuum line popped off or is leaking. I'd clear the codes and try giving the car some vigorous exercise. Maybe find a long steep grade you can power up in third/fourth gear. That should help clear the turbo vanes if they are sticking.

Click to expand...

Check the vacuum pump as well.... not cheap but that was what mine ended up being.