If it has got a Power Commander fitted it is very likely to have a Dynojet O2 Optimizer fitted as well. This is more than likely where the fault lies.

To start with, the early versions of their Optimizer were a bit unreliable can can through up running problems and cause the engine trouble light to show. Dynojet will supply you with a later version if you give them the serial number of your PC unit. Secondly, check the inline connectors where the Optimizer fits in line with the stock O2 sensor's loom: a dodgy connection here will trigger the engine trouble light and error code 24.

Have a look for a small black box plugged into the O2 sensor wiring.

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