Hi all I replced the pre cat left lambda sensor after a heater fault with a Denso DOX 0242 which I was told even though the part number was different this was the correct part with a new number we now get error code P0125 this is a coolant error but I dont think thats the problem my code reader comes up FUEL SYS 1 AND 2 0L-FAULT after about 5 minutes from cold by which point the water temp shows 85 C if you reset the fault the error comes back on after a short time even if the water temp is up at 90 C. Both lambdas are reading between .15v and .8v

What is going on please help

Thanks in advance

Just because the code reader is showing a fault on the Lambda sensor does necessarily mean they themselves are faulty. It could be the exhaust gases are too rich. When cold the ECU will increase the fuelling level but should reduce it when warm. If after clearing the codes the fault only arises when the engines warms up there is a possibility an engine coolant temp sensor may be adrift. It may be worth checking their electrical connections for corrosion or dirt as a poor connection will increase the resistance and send an erroneous signal to the ECU. Remember diagnostic equipment is quite dumb at times - why - because the dumb machine can't tell the difference betwen a poor connection and a duff sensor.

[quote name='Jamesbelfast' post='944581' date='Nov 15 2009, 07:04 PM']Just because the code reader is showing a fault on the Lambda sensor does necessarily mean they themselves are faulty. It could be the exhaust gases are too rich. When cold the ECU will increase the fuelling level but should reduce it when warm. If after clearing the codes the fault only arises when the engines warms up there is a possibility an engine coolant temp sensor may be adrift. It may be worth checking their electrical connections for corrosion or dirt as a poor connection will increase the resistance and send an erroneous signal to the ECU. Remember diagnostic equipment is quite dumb at times - why - because the dumb machine can't tell the difference betwen a poor connection and a duff sensor.[/quote]

Thanks my code reader reads live date and the engine temp is 90 is there more then one sensor if so do you know where to look? I replaced the lambda sensor as the heater had gone open circuit on the fault code and confirmed with a meter.

Thanks again