02 corolla check engine light

nd

Hi, so my newly acquired 02 corolla has a check engine light showing. It is driving great. I brought it to my local garage today to get the fault code that the car was showing. The mechanic did some tests on it and they were fine and he told me that it is nothing to worry about. He thought that the front lambda sensor might be a rear lambda sensor as it had a longer wire than he thought it should have and that that might be causing the check engine light but it was nothing to worry about.

Having checked online a replacement lambda sensor looks to be about 120 euro.

Think I should get the replacement or just not worry about the check engine light?

Saucy McKetchup

Bring it to a mechanic that will do a diagnostics test on it and not just give fob you off for a start

nd

He did test it with his equipment. The readout for the error code said "Catalyst 1". And he tested the emissions and said they were perfect.

Saucy McKetchup

nd wrote: »

He did test it with his equipment. The readout for the error code said "Catalyst 1". And he tested the emissions and said they were perfect.

No really, bring it to a different garage, sounds like he has no clue what he's talking about

joujoujou

nd wrote: »

He did test it with his equipment. The readout for the error code said "Catalyst 1". And he tested the emissions and said they were perfect.

I can test it for free. Where are you located?

nd

Thanks for the offer . But I'm in county Limerick.

joujoujou

Far away I'd say.

Saucy McKetchup

nd wrote: »

Thanks for the offer . But I'm in county Limerick.

What engine code did the mechanics diag equipment show up?

nd

Well he just game me a printout from the equipment. Under description it says "Catalyst 1" and under status says "mem". He cleared the fault yesterday and I've done maybe twenty miles since and it hasn't returned. I have ordered one of those cheap ebay code readers which was probably a waste of money

Saucy McKetchup

nd wrote: »

Well he just game me a printout from the equipment. Under description it says "Catalyst 1" and under status says "mem". He cleared the fault yesterday and I've done maybe twenty miles since and it hasn't returned. I have ordered one of those cheap ebay code readers which was probably a waste of money

Nah they'll work fine, I have one myself, Google is your friend then when codes show up

joujoujou

I've one as well. Does exactly what says on the tin.

nd

So my ebay adapter turned up today. It is giving a P0420 code. Which is "Catalyst System Efficiency Below Threshold (Bank 1)". So after watching a few videos on youtube it seems to test the Catalytic Converter you read the voltage from the o2 sensor in front of and behind the cat.

So I did that using the android torque app and the bluetooth adapter I got and they seem to be giving normal readings. And I tested my fathers new fiesta and it has almost identical readings. The only difference I noticed is the readings in his no1 sensor rise and drop much faster.

Saucy McKetchup

Only thing you can do is check under the car for exhaust leaks, bad wiring etc. might need a new cat, when readings fluctuate it means a sensor is bad, when were air filter and plugs last changed?

dieselbug

Check the values of both sensors with the engine warm. Check at idle speed and at about 2k revs and post up the min, max readings.

how quickly is the front sensor switching, is the rear switching also or giving a steady reading.

nd

dieselbug wrote: »

Check the values of both sensors with the engine warm. Check at idle speed and at about 2k revs and post up the min, max readings.

how quickly is the front sensor switching, is the rear switching also or giving a steady reading.

Thanks.

So once warmed up.

At idle sensor 1 was switching between 0 and approx 0.7 volts. Time between a full rise and fall was approx 2 seconds.

At idle sensor 2 was switching between 0.66v and approx 0.7 volts. Time between a full rise and fall was approx 2 seconds.On one occasion while I was monitoring it over about a minute it dropped to approx 0.4 volts.



At 2k revs sensor 1 was switching between 0.4 and approx 0.7 volts. Time between a full rise and fall was approx 1 second.
At 2k revs sensor 2 was switching between approx 0.6 and 0.7 volts. but occasionally was dropping to about 0.3 volts. Time between a full rise and fall was approx 1 second.

nd

Saucy McKetchup wrote: »

Only thing you can do is check under the car for exhaust leaks, bad wiring etc. might need a new cat, when readings fluctuate it means a sensor is bad, when were air filter and plugs last changed?

I don't know. I know the car was serviced in November and I checked the air filter and it looked very clean. The car passed the nct about a month ago. And my local mechanic said my emissons were spot on, not that that might mean much.

Saucy McKetchup

It's not the CAT so, if it was me I'd get a sensor from a breakers and try that

PADRAIC.M

That code is for deterioration of your catalyst, but reading your compared o2 sensor reading your Cat looks good, your rear sensor should be reading closer 0.5v but this is a very common problem. Maybe try rear sensor, also if you could post up your engine ecu part number I can check if it has the right logic,

nd

Thanks. I've been googling to try to find the location of the corolla ecu to get the part number but havn't found it. If I do I'll post it.

ofcork

Is that the torque pro app you are using and what Bluetooth adapter did you get,have that code on my avensis over 4 years.

nd

Yep. The lite version doesn't show you live sensor data as far as i can see.

i got this adapter

http://www.ebay.ie/itm/121198580820?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

joujoujou

nd wrote: »

Thanks. I've been googling to try to find the location of the corolla ecu to get the part number but havn't found it. If I do I'll post it.

www.toyodiy.com/parts/q.html

Enter your VIN number, click on result, go to electrical - electronic fuel injection system and read the number associated with "computer, engine control" (or something called like) - it's your ECU number (like 89661-0W130 etc).

nd

Thanks again. That seems to be showing two numbers.

89661-02730 PART NUMBER LABEL=89661-02730
89661-02740 PART NUMBER LABEL=89661-02740

http://www.toyodiy.com/parts/p_E_200202_TOYOTA_COROLLA_ZZE120R-DHMDKW_8404.html

joujoujou

That's the problem - it's one or another.

The only way to make sure is to get onto it and read the label.

Saucy McKetchup

nd wrote: »

Thanks. I've been googling to try to find the location of the corolla ecu to get the part number but havn't found it. If I do I'll post it.

Should be under the glovebox

nd

I figured out how to record the graphs from the torque app.

This was after a long drive so the engine was good and hot. In 5th gear on a straight road at about 2k revs.

The top graph is the front o2 sensor and the bottom the back.

nd

And I found the ecu.Is it under the glovebox. Thanks SM. It's 89661-02730

nd

So I took the font sensor out to have a look and to see if I could see any part number on it.

The main thing i saw on it was 05 yaris was written on it. So I'm assuming at some stage a garage put a yaris senor in it from a breakers. Anyone know if the 05 yaris front sensor is compatible with the 02 corolla?

Saucy McKetchup

You get a part number? There's a fairly high chance that it'd be compatible

nd

The only numbers I could see stamped on it were 491161. But after searching various places that isn't showing up anything.

joujoujou

nd wrote: »

[...] Anyone know if the 05 yaris front sensor is compatible with the 02 corolla?

You already got the link - check o2 sensor's number (electrical - switch and relay - oxygen sensor), then go to main page and use cross-reference feature.

nd

So an update. I bought a new front 02 sensor and fitted it. Cleared the fault. Drove for about a week and no check engine light. so thought that was it solved. But it then came on again. So I fitted the sensor that was the front sensor to the back. Had to alter the wiring.

Cleared the fault again and a few days later it returned.

So I'm thinking the cat probably isn't 100%. But perhaps it's plenty good enough to pass the nct and the ecu's check are just very strict. But am also wondering should I be budgeting for a replacement cat.

Noccy_Mondy

Are you sure the tape didn't just fall off? :P :pac:

joujoujou

What's the fault number?

nd

Just the P0420.

joujoujou

What revs (up to) you're usually drive at?

These engines like to be run on high revs (of course expect more fuel and oil to go). That apllies to cat converters as well.

My rolla has approx. 200k miles done and its factory fitted cat still runs OK.

Before you buy a new cat, maybe try this?

https://www.youtube.com/watch?v=5icTmYItwiE

nd

Thanks. Yeah the nct isn't due to feb 15 so I wouldn't be buying a cat soon even if I need one. As far as I know an inefficient cat wouldn't do any harm to the car. I don't think I'm brave enough at the moment to put lacquer thinner into the petrol thank

ofcork

My avensis passed the nct in 2012 with the same code,turned light off and ran dipetane through it and no prob,going again next week so hopefully same result.

nd

Let us know how it goes! yeah maybe the ecu checks are overly sensitive.

ofcork

Passed the nct today no problem,turned light off and ran dipetane through it and was done and tested while others were still waiting!

nd

Great news!

nd

A strange update on this. So the light used to come on a couple of times a week and I'd turn it off. Recently an ignition coil failed of a saturday evening. I couldn't get a replacement until Monday so drove it on 3 cylinders until then. After reading some stuff on the internet mid way through Sunday I disconnected the fuel injector on the cylinder with the failed coil as I read it was bad to be sending unburnt fuel into the exhaust.

Since then the check engine light hasn't come on. it might be a month now. I've used my scantool and the rear o2 sensor is still working fine. i'm wondering has the unburnt fuel being send into the exhaust cleaned the cat or burned off something in it?

joujoujou

At first, unburnt petrol sent to exhaust would burn out residue (a bit) off the cat. But very quickly after that it'd burn out a cat itself. Nothing else.