147 JTD 16v - MCSF, Error P0238 - Alfa Romeo Forum
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147 JTD 16v - MCSF, Error P0238

Having got my new 147 repaired, painted and back on the road the first time out driving it I got the dreaded MCSF error and loss of power. Reading the code it was P0238 - "Turbo charger boost circuit, input high". I have changed the MAP sensor, reset the error and the problem remains.

However, the point at which I get the MCSF seems to be a little higher in the rev range and with more boost than previous; the first time was accelerating moderately in 3rd gear. The next time it was in 4th with almost full throttle going up small rise, and just the last time it was at full throttle in 4th. Before the error occurs and it goes into limp mode, the car accelerates extremely well. I suppose I could continue driving and resetting each time to see if it gradually goes away (something freeing off, perhaps?), but it's annoying, and expensive if I have to keep doing it - also a bit worrying if it should happen when flying along the A1M....

Before I bought the car I know it had sat for at least 6 months, and I wonder if that, along with the possibility of it having been driven as if by miss daisy by the previous owner (no evidence for that though), has caused the problem?

What areas of the turbo system should I look at first? Are there any key parts (actuator, wastegate, the vanes of the fancy VNT system?) that always play up first on these models?

Any help gratefully received!
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(Post Link) post #2 of 5 Old 08-10-08 Thread Starter
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Re: 147 JTD 16v - MCSF, Error P0238

I've driven the car again over the last 2 days - actually given it a good thrashing - and the fault seems to have gone now; no problems with full boost in any gears now, and the MCSF error is not beeping at me and cutting power anymore.

I'll reset the codes one last time, but it looks like it was in fact something partially seized most likely caused by lack of use or lack of being driven as it should be.
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Re: 147 JTD 16v - MCSF, Error P0238

Sounds like stuck vanes in the VNT system causing overboost. If it has gone away by itself then thats great
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Re: 147 JTD 16v - MCSF, Error P0238

Take a visual look at the turbo vanes on both sides (inlet and exhaust), if a blade has been chipped and it was wedging the turbo then you'd get that problem, if the chip subsiquently escaped then the problem would go, but you'd have an imballanced turbo and that will wreck the bearing.
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Re: 147 JTD 16v - MCSF, Error P0238

Hey Megatron-UK

I had exactly the same problem..

Read my Post..


It started as quite intermittent, like a year betwen problems, then every couple of weeks, then every other day, then every time you booted it.

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147 , 16v , error , jtd , mcsf , p0238

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