Need more description on codes

[marvsho17]

While getting the low coolant light because of a leaky water pump, last night I got the good ol cel.


21 - Engine Coolant Temperature (ECT) sensor out of range

25 - Knock sensor not tested (ignore if not pinging)

73 - Rerun test if 73 is still output replace TPS No Throttle Position Sensor (TPS) change in "goose" test. Must get at least 25% throttle rotation

91 - System running lean Transmission SS 1 circuit/solenoid problem

The 21 25 73 aren't making me nervous, but what is this 91?

 

[Rockledge]

Code 91 means your left O2 sensor is indicating a lean condition.

Could be a bad 02 sensor (or a problem with the circuit), but it could also mean the engine is running lean on that side, in which case the usual suspects have to be considered (vacuum leak, fuel delivery issue, etc).

 

[projectSHO89]

If you did not pre-heat the cats, you will get a 91.

The other codes appear to be due to an improperly executed goos test. The 21 is probably due to a failure to have the engine at operating tep.

Steve