Hi all,
The above vehicle came into me with dtc's 17526 & 16525 which both appear to refer to HO2S bank 1 sensor 2 open circuit. Everything seemed ok so the sensor was replaced (genuine) and the code cleared. The mil came on fairly soon after but the customer didn't return to me for a while. At the next scan both these codes were present and also 16785, EGR low flow, and 17852 EGR position sensor. At this point the EGR was replaced (but not adapted). Two codes have now returned, 16525 and 16785. I am going to ignore 16785 at the moment due to the adaption but I have checked the HO2S2 circuit and can find no faults. I have scoped the sensor heater circuit at the ecu pin (No 13) and found the duty cycle to be about 10%. AD doesn't give a duty cycle for this pin but gives 58% for HO2S1 (pin 1), which it is. I know that they are different types of O2 sensors but I would have thought the heater circuit duty cycle would be about the same for both of them. Does anyone know any different.
Regards, Bryan.