[Midlife_C]

Hey guys, need some advice on error codes.

2010 N55 6MT with JB4 (on map 5) and charge pipe installed 18 months ago, spark plugs replaced 6 months ago. Car has been driving fine, no errors. 54,000 km.

Now once in two weeks I get Engine Fault with Reduced Power. Restarting the car fixes it, even with JB4 set to not clear the error codes.
The fault comes up in innocent situations – starting to move in traffic, starting a right turn. Did several launches and WOTs in 2nd and 3rd gear – no problems, no errors, goes like a rocket.

Not sure if I read the codes correctly using JB4 (the instructions were for US M/h speedo, not km/h).
The speedo showed the following km/h:
20 - 120 - 90 - 0
20 - 120 - 100 - 30
20 - 120 - 50 – 80

I assume the codes are (am I correct?):

2c90 Blow-off valve, mechanics: Jammed closed.
The diagnostic function monitors the compressor bypass valve to determine if it is seizing in its closed position.

2ca3 Wastegate valve, activation: Line disconnection.
The diagnostic function monitors the electrical wire from the DME to the electropneumatic pressure converter.

2c58 Boost pressure control, deactivation: Boost-pressure build-up blocked.
The diagnostic function monitors the DME's deactivation of active boost.

Do these codes make sense?
I was thinking the coils need replacing but the codes seem to have no relation to that.
My battery is still original – maybe needs replacement? Can old battery cause such issues?

[Digitalism]

Not much help but maybe remove the JB4 for a week or two and see if the problem is still there.

[Ken Oath]

Check the charge pipe bungs are still in place.

[Midlife_C]

Originally Posted by Digitalism

Not much help but maybe remove the JB4 for a week or two and see if the problem is still there.

I might try that if nothing else works... Would be pretty miserable to drive around without JB4, I am so used to it now.

Originally Posted by Ken Oath

Check the charge pipe bungs are still in place.

I had a look this morning, all seems to be good. Clamps are tight. The metal clip on the engine side of the pipe can be moved around a bit, but I do not think it is supposed to be super tight?

[aaron_]

I had the top and bottom code on my car. Is think 2c90 is a jb4 code and not a Problem. I think the bottom code might be a bad boost solenoid. It's a cheap and easy part to replace. Do silicone vacuum lines at the same time

I had the same problem, reduced power not a wot and the bottom code. Doing the above fixed it

As for the middle code, no idea.

I'd try what I said above and cross my fingers it somehow fixes the middle code as well

[Midlife_C]

Originally Posted by aaron_

I had the top and bottom code on my car. Is think 2c90 is a jb4 code and not a Problem.

Thanks Aaron, yes I can see 2c90 appearing all the time on its own if I have JB4 set to not clear the codes. Found this explanation on the interwebs:

... the technical cause is the JB does not reduce the boost signal when letting off the gas. They've found this allows better overall diverter function at the higher boost levels (it opens more aggressively) but as a side effect does trip that hidden code which auto clear takes care of for you...

Originally Posted by aaron_

I think the bottom code might be a bad boost solenoid. It's a cheap and easy part to replace. Do silicone vacuum lines at the same time.

Thanks, I might do that, will chat with the guys at Advan.

May still try to replace the battery first - all 3 faults happened after weekends, when the car wasn't driven. Maybe when taking off slowly at low RPM the alternator not producing enough current and the battery is too old to keep up, causing this covfefe.

[aaron_]

Just check battery voltage first (engine off and on) before changing it unnecessarily.

[EB89]

Originally Posted by Digitalism

Not much help but maybe remove the JB4 for a week or two and see if the problem is still there.

Do this^