94 FZJ80 - Code 12 and 21

[cmcmill01]

So decided to see if there where any codes reported on my 94 FZJ80 OBD1, got codes 12 and 21!!
I think the codes relate to:
12 Knock Control Sensor signal
21 Oxygen sensor

Anybody have any good ideas on how to fix these??
Is there a way to check which O2 sensor? Also when I got the exhaust replaced I think they welded the O2 sensor to the exhaust!!
What is the knock Control sensor when its at home?

Cheers
Craig

 

[Gary820]

There's only 1 oxygen sensor which should be just in front of the cats.
The knock sensor will be bolted to the engine block and detects knock/pinking. It tells the ecu if it's picking something up and alters the ignition timing.

 

[cmcmill01]

Gary mine has 4 !!! 2 in front and 2 behind the cat!! It's an import!!

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[Gary820]

Not seen that set up before! Usually 2 cats in line. What country is it from!!??

Is there any other info with the fault codes. Pre or post cat oxygen sensor, bank 1/bank 2?

Is it just a code reader or can you get live data on screen too?

 

[cmcmill01]

OBD1 so it's a paper clip and count the flashes job!!


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[Gary820]

Does it run OK? Possibly codes got stored when you had exhaust done?
If oxygen sensor off fuel consumption can get worse, emissions high etc. Can check voltage of sensors when engine running or an oscilloscope to see what they're doing.

I use my laptop with mine and can get live data but my ecu isn't standard (not a lot of data but can get engine sensor/fuelling info)