Hi folks,

I was hoping someone might be able to help with a few fault codes on a 1.3 Ford KA (2006) which is showing the following fault codes:

P0171 - System too lean Bank 1

P0030 - HO2S - Heater Control Circuit - HO2S11 Circuit Malfunction

P0132 - HO2S11 - Circuit High Voltage, signal circuit shorted to VBATT

I was led to believe that the vehicle had a faulty Oxygen Sensor so I replaced it with a NGK sensor specific to the KA.

The symptoms are: the car will not always start first time and when it does start in the cold it labours (sometimes stalls) and if you pull of in that state the car is seriously lacking power for the first few miles. As soon as the engine is warm it runs ok.

The voltage range on the upstream (pre-cat) oxygen sensor fluctuates between 0.07 and 0.59

Any suggestions will be appreciated.

Many thanks

Steve

So since replacing upstream , you still have the same dtcs?

Yes Ian, I have cleared the codes but they register again immediately.

have you got a multimeter, if you have then disconnect the sensor and check ohms reading on the heater wires to the sensor,if you have ngk then they are the 2white wires i think , your checking the heater resistance of the new sensor in case you have faulty new sensor, ohms up to 30 ohms ok.

switch ign on and check for 12v at violet/yellow wire at connector,if not chack fuse 30

as you saying the voltage is fluctuating when running, im assuming the sensing wiring is ok

Not sure if these more indept descriptions might help you