Good afternoon all,
I am a newbie looking for some advice on Mondeo 2.0L petrol; year 2001 (Y registration)
The MIL light came on; garage diagnosed "lambda sensor". I spotted the post cat one and replaced it with a universal (4 lead) one, then disconnected battery but after 2 engine run cycles the MIL light came on. Found the lamba sensor on the exhaust manifold and replaced that, repeated baterry disconnect but after 2 engine run cycles the MIL light came on again.
I then bought a DTC code reader; this displays "P0135 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)"
Is this the exhaust manifold sensor? I know that the two white leads are sensor heating. Has anyone had a similar experience and what was the solution? Does anyone know how the heater is switched; I imagine it must be controlled by the ECU but is there a seperate timed relay involved or is all control within the ECU. Of course a broken wire or dodgy connector block are also candidates. Any guidance appreciated.