Problem
Calibration of the lambda sensor fails. It reads 16% O2 on LCD display page 7, even with calibration constant 255.
Should the lambda heater FET be replaced?
The heater seems to work. It only turns on with the engine running, and has to be manually turned on to heat up without the engine running (as it should). The volteage behaviour at the heater pins works like this : it starts out with 4V then quickly ramps up to 10V and slowly increases to 12V at which point the sensor is glowing light orange (hot!).
As with all FETs, a failed heater FET would probably short to ground, causing constantly heating the sensor with the ignition on. This is not really the case as it needs to be turned on. Could the FET just have problems turning off ?
The system uses a v3harness and was fine last summer and the car was brought out of storage, ran fine that time and the second time it was started the sensor didn't work. A new sensor reveals the same problem, so the problem is harness/Genboard or a configuration problem. The configuration has not been touched except for the calibration constant which is not making any sense at this point.
Config
Firmware : 1.0.78
Display with heater on
