540 Engine check light codes
I have a 99 540i and the engine check light is on. Unfortunately the closest BMW delaer is 2 hours away, but I do have a good and honest independent mechanic who was BMW trained. Unfortunately he does not have full access to all their diagnostic equipment and manuals.
At the present time my car is running fine, but the engine check light keeps coming back after the faults are cleared, and I need the faults gone in order to get an emissions test done prior to license renewal next month.
If anyone can help with ideas about the cause of the faults it would be greatly appreciated.
The faults are:
1) Fuel trim at part load below threshold, multiplicative converter bank 1;
2) Fuel trim at part load below threshold, multiplicative converter bank 2;
3)Electronic thermostat control final stage.
Thanks in advance for any suggestions.