Celica Gen 7 Engine Malfunction Light

[bluecelica]

Hi,

The "malfunction indicator light" has just come on whilst driving my celica, has this happened to anyone and can they give advice on what to do? I'm particularly interested in the following:

1. I suppose I should take it to the garage so they can say what they think is wrong, but I'm worried that they will suggest changing something and it won't actually make any difference (the car seems to drive ok).

2. Can I try and reset it by disconnecting the Battery for 10 secs or whatever? (and is there a code on my stereo that will stop it from working if I disconnect the Battery, its a 99 car with the sony stereo).

3. This seems to be a common problem with other toyotas, is it a known problem for the gen 7 celica?

Any help would be greatly appreciated!

Thanks

[holly7]

Hi,

The "malfunction indicator light" has just come on whilst driving my celica, has this happened to anyone and can they give advice on what to do? I'm particularly interested in the following:

1. I suppose I should take it to the garage so they can say what they think is wrong, but I'm worried that they will suggest changing something and it won't actually make any difference (the car seems to drive ok).

2. Can I try and reset it by disconnecting the battery for 10 secs or whatever? (and is there a code on my stereo that will stop it from working if I disconnect the battery, its a 99 car with the sony stereo).

3. This seems to be a common problem with other toyotas, is it a known problem for the gen 7 celica?

Any help would be greatly appreciated!

Look in your handbook,I think some lights double as "service due" indicators.

[DefiantFrog]

Yep, take it to a garage, or someone else with a diagnostics kit and some intelligence!

Yep, disconnecting your Battery will reset your ECU. I think its only minutes before the ECU is set back, but 1/2 hour will definately cover it! No stereo codes to worry about.

Common things on the pre-face lift - Air flow sensor is knackered, or you're about to run your engine without any oil in it! We aren't fortunate enough to get a Service-Due warning...

Welcome to the club by the way!

[bluecelica]

Thanks for the advice, i've booked it in for a diagnostics check (will check the oil first just in case - it was ok last week...)

I will post the garage's findings.

Cheers!

[chris202]

Catalytic convertor possibly gubbed - noticed a post about this over on celica-club and one of the members had the same problem :) cheers Aberdeen dude

[spotipus]

also just noticed this on celica club

looks like you could be in for an expensive job

hopefully not though

[bluecelica]

Having done the diagnostic check the garage say it's a problem with an O2 sensor (apparently there is a front and a rear sensor) near the exhaust manifold / catalytic converter (sorry not sure which). Apparently they go wrong after about 40-50k miles.

They say it's not having an adverse effect on the running of the engine (according to the fault code?) so it's worth just waiting a couple of months to see if the light goes out by itself.

Have to wait and see.....

Cheers!

[DefiantFrog]

Sounds about right! I'm coming up to 60k, and not had it yet, but fully expect it while I own the car. Shouldn't cause you any major grief in the short term, but I doubt it will go out all by itself...? From what I remember though I think its a bit costly to replace, just so you're warned...

[bod]

Hi I've had the same problem - there's some of my and others findings along with money savings DIY fixes here:

http://toyotaownersclub.com/forums/index.p...mp;#entry580352

[bluecelica]

Thanks for the link bod - there's some good stuff on there!

I think one of your last posts said you were still having problems with the oxygen sensor, I've done a quick search on the forums and there seems to be a fairly significant problem with Previas with a very similar problem. Try this link:

Previa Posts

Very interestingly there are several posts from a toyota mechanic "Ray99", including this explanation (I don't know how similar the Previa's catalytic converter and oxygen sensors system is to our celica's):

Hi you Previa owners. I'm a Toyota technician and I can give you all some help with understanding what's going on with your Previas. To understand the MIL ( Malfunction Indicator Light) we need to start with the way the ECU (Engine Control Unit) controls the emissions. When the engine is up to operating temperature, the ECU is looking for a signal from the pre-cat sensors. The sensors are sensitive to oxygen in the exhaust gas. If there is oxygen above a certain level, the ECU richens the mixture until the oxygen level starts to fall. When the oxygen has fallen below a certain level, the ECU starts to weaken the mixture and the oxygen level starts to rise and the cycle starts again. All this happens several times per second at cruising speed and makes the exhaust gas look as if it is stable in its gas content. The mixture is ocillating either side of the perfect ratio, but by so little that it is difficult to measure. Two sensors are used to give finer control of the emissions. Cylinders 1 and 4 share sensor 1, bank 1. Cylinders 2 and 3 share sensor 1, bank 2. These two sensors monitor the mixture strength as the exhaust gas goes into the cat. The other two sensors- sensor 2, bank 1, and sensor 2, bank 2, monitor the exhaust gas before it is released to the atmosphere. This is a requirement now for a Euro 4 engine. If these two post cat sensors detect any oxygen in the exhaust, the ECU assumes that the cat isn't working and lights the MIL. However, under certain circumstances, usually on a long motorway trip at a steady throttle, the ECU will see variations in the signals from the post cat sensors that are normal, but a little larger that expected. The ECU lights the MIL and you come and see us. The original fix was to reprogram the ECU and allow the larger signals, before the ECU decides there is a cat fault. We also discovered that cats were indeed breaking up and sensors were giving faulty signals. So the complete fix was- reprogram ECU, replace cat and all 4 sensors. You can have your MIL on and still pass the MOT emissions test.

Previas also suffer from an unusual fault with the MAP sensor. There is a small diameter vacuum pipe from the inlet manifold to the sensor on the left hand inner wing/chassis area. This pipe has been known to fill with oil and gives hesitation and high fuel consumption. Not all Previas suffer, but worth checking if you have unexpained high fuel consumption. Sorry this has been a very long and wordy post- especially for a first post, but I felt it was worth taking the time to expain

Regards Ray