How do I tell what specific problem is causing the check engine light?

It only comes on whilst accelerating, then goes off again. I was told to replace the Oxygen Sensor and I'm planning on doing it, but apparently the check engine light doesn't come on for Magnas after 1992 if it's a problem with the Oxygen Sensor, and mine's a 1993 TR. It was also suggested that I replace the ECU.

What's the most likely problem causing the light to come on whilst accelerating? I want the problem fixed right now and can't take it to a mechanic because the car isn't roadworthy yet and honestly, it costs way too much. After buying a car, buying parts, buying a sound system, keeping money for a service, tune-up, oil change, detailing and registration I would love to be able to fix this problem myself.

What the the engine symbol light indicates when it comes on

1. Engine control unit
* 2. Oxygen sensor
3. Air-flow sensor
4. Intake air temperature sensor
5. Throttle position sensor
6. Engine coolant temperature sensor
7. Crank angle sensor
8. Top dead centre sensor
9. Knock sensor
10. Ignition timing adjustment signal
11. Injector
Caution: - The engine warning lamp also comes on when the terminal for ignition timing adjustment is
earthed during ignition timing adjustment.
*Note - The 0' sensor on 4 cylinder models built after February 1992 does not activate the engine
warning lamp

What the the engine symbol light indicates when it comes on

1. Engine control unit
* 2. Oxygen sensor
3. Air-flow sensor
4. Intake air temperature sensor
5. Throttle position sensor
6. Engine coolant temperature sensor
7. Crank angle sensor
8. Top dead centre sensor
9. Knock sensor
10. Ignition timing adjustment signal
11. Injector
Caution: - The engine warning lamp also comes on when the terminal for ignition timing adjustment is
earthed during ignition timing adjustment.
*Note - The 0' sensor on 4 cylinder models built after February 1992 does not activate the engine
warning lamp

Yeah I've seen that, thanks though. What I wanted to know was is someone else had the problem with it specifically coming on only while accelerating, because I can't get the ODBII codes until Wednesday.

Mate I dont think second gen have a ODBII port as there are a fairly old unit. You read the fault code by using a analogue volt meter or a test light :)

Go to www.madmagna.com and look at the tech section, there is a write up on how to do this

Mate I dont think second gen have a ODBII port as there are a fairly old unit. You read the fault code by using a analogue volt meter or a test light :)

Really? I thought the little white plug near the fuse box thing near the driver's right foot was it. Thanks though, I'll have a look.

Analogue multimeter across 2 of the pins on that plug, pulses tell you the error code, if one is logged.

Why not check simple stuff first, like ignition timing, air leaks etc? If your ignition timing is too far advanced, it will give the knock sensor a good workout under acceleration.

Go to www.madmagna.com and look at the tech section, there is a write up on how to do this

Thanks, that's really helpful, might have to get myself an LED test light.


Analogue multimeter across 2 of the pins on that plug, pulses tell you the error code, if one is logged.

Why not check simple stuff first, like ignition timing, air leaks etc? If your ignition timing is too far advanced, it will give the knock sensor a good workout under acceleration.

I've got a digital multimeter, that wouldn't work would it? Yeah I'll check most of that, I'd like to know the specific problem though.

Digital wont work. Manual says LED or analogue multimeter. Dick Smith has cheap ones.

Digital wont work. Manual says LED or analogue multimeter. Dick Smith has cheap ones.

I really hate public holidays, I hope Dick Smith are open today.

I really hate public holidays, I hope Dick Smith are open today.

And it's not. So I guess I wont know until tomorrow then. Thanks for all the help guys.

It's a pity, I have a bunch of LED globes, if only I had a resistor I could do it myself. All a test light is is an LED with two long bits of wire and a resistor on one side.