regarding this code, after spending over £2000, i have found the problem, the wiring from the engine to the ecu becomes brittle and shorts out, if you replace the wiring, that should fix your problem, i must add the reason for the cost of £2000, my c5 had the following parts, new engine, ecu tested, new turbo, new intercooler, complete new sensors, complete new pipes, new partifcate filter, and lasty was the wiring, which solved my problem, please note i am a mechanic by trade so £2000 to me would be about £3750 retail.