Steve Rothwell answering your ENGINE MANAGEMENT queries
BMW 1-SERIES
Q Many thanks for your previous advice on my sons 2011 BMW 116i. I found the turbo intake pipe brittle and leaking. This has been replaced and was clear of faults but now the management light is on again with P0030 fault code.
I believe this relates to the pre-cat oxygen sensor heater circuit. The sensor is a five-wire one with the colours red, yellow, black, grey and white. Could you advise me on testing this type and if there is no power to the heater circuit what number the fuse maybe?
A The code P0030 as you have correctly discovered refers to the Heated Oxygen Sensor (HO2S) 1, bank 1, heater control - circuit malfunction. This may be the heater unit within the sensor or the wiring to and from the sensor.
The first test would be to check the continuity of the heater in the sensor, and this can be done by using an ohm meter on the two heater circuit wires, I would expect to see a reading of around 3-4 ohms. An open circuit reading would indicate a failure and the sensor should be renewed.
The grey and white wires should be the heater with the grey being the positive (+) and the white being the negative (-).
If there is a circuit through the 02 sensor, then the feed and earth should be checked. If there is no feed then this will be an engine control module problem as according to the details I have from Autodata, the 02 heater circuit is not directly fused, but to ensure the problem is not a fuse, fuse number 23 in the engine bay fusebox should be checked.
It is also possible that your BMW has a small separate fusebox located at the rear of the engine bay to the offside containing one relay and seven fuses, if this is the case these should also be checked as if fitted they do relate to the engine control systems. If no failed fuses can be found, then in this case the next step would be to remove the engine control module plug and check the connections. If nothing can be found at this stage, then sending the ECU for testing may be required.
MG ZT-T
Q I can’t get my MG ZT-T V8 to run properly. When it starts it revs immediately to about 2000rpm and then it drops down to about 800rpm but it is very rough and surges. If you accelerate up to 3000rpm it runs fine but once you let the revs drop and engage drive there is little power.
I changed the throttle body and the inlet manifold chamber for second-hand ones. The throttle body came with the sensors and the inlet manifold chamber came from a car allegedly with only 50,000 miles on the clock and with new Variable Inlet System (VIS) motors. I managed to borrow a Snap-on diagnostic machine and the codes that it is throwing up are: P0151, P0131 and P0108. I think they are all to do with the air/fuel mixture which would tend
