engine codes

[Chaingun]

got a combination of 21 Oxygen Sensor Signal, 42 Vehicle Speed Sensor Signal, 43 Starter Signal, and 51 Switch Signal, the only thing i see in common on all of these items is the ECU. I'd planned to replace the Oxygen sensor next weekend but i'm not sure where to check the speed sensor and it's circuit and the items listed on the starter signal can be checked at the ecu, but i haven't had a chance to pull it yet. has anyone experienced these codes in tandem before?

 

[jetjock]

Not sure what you meant by "tandem" but the diag system always displays codes starting with the lowest number regardless of which order they were set.

21 is usually the O2 sensor heater or heater wiring but can be other things O2 related depending on model year. I'd check it before changing. O2 sensors are one of the most needlessly replaced parts on cars.

42 is a lack of input from the magnetic reed switch (assuming an analog dash) integral to the speedo. Can be anything from a busted speedo cable to bad wiring. The signal can be checked at the ECU or by using the cruise control diagnostics. The cable can be checked by looking at the speedo when the vehicle is moving (duh).

43 is no input of signal STA to the ECU when cranking. Usually wiring or from push starting the car.

51 is usually the TPS but it can also be the AC button is on with the engine off. Could also be a faulty AC amplifier or neutral start switch. A quick way of checking is to leave the system in diag and start the engine. If the code remains present with the engine running it's the TPS.

The first step is to clear the codes (they may be old) and see what comes back. This doesn't apply to 51 of course. It can't be cleared because it doesn't get set...

 

[Chaingun]

The o2 sensor is getting power to the yellow plug but it's not heating itself like it should, that's why i'd planned to replace it. The speedo isn't working ATM because i haven't put the cable back in, but i though that even with an analog dash there was a speed sensor on the transmission too, not sure cause this is a 5 speed conversion. Also the cruise control has been removed as it was A. Ugly as hell B. not working anyway. Now that it's gone the ABS light doesn't come on either so that's a plus.

I have had to roll start the car occasionally due to it dieing after it warms up, which i think is related to the 51 ie the TPS adjustment being off, that could also be due to the lack of a neutral start switch. If you can tell me which of these plugs the NSS should be wired into i can wire the clutch safety switch to it instead.


I'll adjust the TPS and go from there then report back. It seems like most of my codes are simply stuff related to the PO's tranny swap.

 

[jetjock]

Interesting. Rather than continue I'll simply point out the enormous irony to be found in the last line of your sig...

 

[Chaingun]

hmmm irony not really my thing so i guess i don't get it