Diagnostics Doctor
FORD FUSION
02 Heater control circuit
Q My neighbour has a 2006 Ford Fusion 1.4 petrol with 80,000 miles on the clock. It has been regularly serviced and the cambelt changed. The EML came on a couple of days ago and a check with an Autel MS509 shows fault code P0030 – HO2S Heater Control Circuit – Bank 1 – Sensor 1. I believe this is the heater side of the upstream Lambda sensor. Does the sensor heater run continuously or just at start-up?
I reset the EML and after 37 miles it returned. Live data shows O2B1 S1 (v) 0.455 and O2B1 S2 (v) 0.405. The car drives fine.
He is in the process of buying another car so does not intend keeping the Fusion more than a couple of weeks, but is it OK to drive it in the meantime? Will it go into limp-mode if he continues using it
Jim Millard
A The heater circuit for the 02 sensor will only operate as needed when the engine is cold, but the circuit will be continuously monitored and so any open circuit will trigger a fault code. The code P0030 does as you have discovered indicate that the Heated Oxygen Sensor (HO2S) 1, bank 1, does have a circuit malfunction.
The code does not mean that the 02 sensor is not operating correctly and so the mixture control should be correct.
As the fault code does take a while to reappear then I would not expect the problem to be an open circuit, but it would be worth checking the connecting plug to the 02 sensor to ensure that a poor connection is not making and breaking.
If the wiring does appear to be in good order, then I would expect the fault may
