my car nissan almera 2001, 1.5, mamual, engine warning light on for certain time,according to snap on code reader, fault code was p0141 heater circuit problem on bank 1 oxygen sensor 2.
things i"ve done:
1. managed to change no. 2 sensor, light still on, drive round blocks 10 mins, light still on
2. :::: to check the voltage of no 1. sensor(by the cat), it read 356mv, try to
check no.2 sensor volt, weather getting dark, and 4 wires on the plug, dont know which is which, gave up.(when checking no.1 sensor volt, eng was idling speed)
3. all wires ,fues, seems ok, except ecm plug connection( could not find location)
please help :
1. how to repair this circuit problem
2. do i have to check all the sensors one by one
3. how to check ecm
4. is the mixture too lean, how to tune it up
5. location of ecm unit
6. if battery is disconneted,will the fault codes come back again
7. by the right hand side of engine bay, there is a small rectangular rely box,one main
relay missing, doest it matter
8. please show me the right path to get rid this light,many many thanks!!!!!!!!!!!!!!!!!!

Country: United Kingdom
Make: Nissan/almera
Year: 2001
Engine: 1.5 l

Already Tried:
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