Member Since: 30 Jul 2022
Location: Paris
Posts: 12
Turbo circuit issue - p0235-94 fault - and no other code
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Hi All !
Another episode in my struggle to have the TDV6 3.0 operate reliably in my D4. Mostly issues on turbo circuits. Car has 260 000 kms, with original turbos (and crankshaft !). Bought it at 230 000 kms. Did a ton on maintenance on it.
For the turbo circuit, changed in multiple iterations :
- CSOV (POO33-00 default)
- intake manifolds (preventive)
- TSOV (secondary turbo actuator) - had codes P22D277 and P22CF71 (was stuck)
All went well for a while and car got back to normal performance.
Did a long ride yesterday, and all of a sudden, I get a p0235-94 (Turbocharger/Supercharger boost sensor A circuit - Component Failure - unexpected operation).
I have an IIDtool so I reset the code, but it came back randomly pretty quickly, typically when needing extra power.
I am bit puzzled as this code comes "alone" , no other DTC.
Looking at the DTC guide attached, if the CSOV or TSOV was stuck I would get other codes.
Haven't had time to look in the engine bay yet. I will try to clean the MAP sensor and check for vacuum leaks.
Any hint ?
Thanks, Alex.
12th Apr 2025 8:36 am
PROFSR G
Member Since: 06 Mar 2017
Location: Gulf of MEXICO
Posts: 5382
Clogged or duff MAP sensor or connector/wiring fault is a first port of call for that code.
Also, sticky turbo vanes caused primarily by short journey times! Clean the MAP sensor with brake or carb cleaner (do not poke anything into it!) and check carefully the connector and harness. Then stick an additive in the tank and blast it down a motorway for 20 or 30 mins. yµ (idµ - eAµ) ψ=mψ
12th Apr 2025 4:49 pm
Alex_J
Member Since: 30 Jul 2022
Location: Paris
Posts: 12
Thanks ! Will try with the map cleaning !
What's weird is that when I log the manifold pressure with the IID tool it doesn't seem to show any issue.
Anybody has any picture on how to best check the vacuum lines ? I don't really see easily where they are...
12th Apr 2025 5:26 pm
Alex_J
Member Since: 30 Jul 2022
Location: Paris
Posts: 12
Quick update !
Changed the map sensor (old one was original Hitachi) with a new Delphi one (way cheaper 30 quids instead of over 90 quids - relatively cheap to "risk" a useless part swap).
So far, it seems to have cured the issue. Went around for a quick trip this morning and quite floored the the throttle on the highway repeatedly, and no Restricted Performance.
Will have to test it on one of my long cross country trips to the Alps to see whether this confirms the cure.
Will keep this post updated if it gets back to the red triangle !
21st Apr 2025 7:18 am
PROFSR G
Member Since: 06 Mar 2017
Location: Gulf of MEXICO
Posts: 5382
Sounds like you found the problem, now just clean it at service times as per my earlier post. yµ (idµ - eAµ) ψ=mψ
21st Apr 2025 2:32 pm
Alex_J
Member Since: 30 Jul 2022
Location: Paris
Posts: 12
Thanks for the tip indeed ! have a great day
21st Apr 2025 5:18 pm
Alex_J
Member Since: 30 Jul 2022
Location: Paris
Posts: 12
Finally, that damn code re-appeared... after like 2000 kms... crazy ! but it comes much less often...
I've now order the MAP sensor tied to the 2nd turbo. will swap it over we and see if it helps
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