2X O2 Sensors Replaced : Eml Back On...?

[Lizzi]

Hi. Well after 5 weeks of owning my Avensis, I've hit a problem.

Two weeks into ownership the EML came on. It was cleared by Mr T, but a week later it was back on, so they replaced both O2 sensors under warranty.

Well last night the EML came back on again. Its the same as before:- It just stays on after starting the engine. (IE Doesn't suddenly pop up whilst driving along.) Still drives really smoothly, and no oil consumption. (So far anyway!) - Mileage is only at 40,000.

Have phoned the dealership, and they say that probably the other 2 O2 sensors need changing as well, as when one fails it puts 'pressure' on the others. Does that sound right, or an I being taken for a ride here? Would it be feasable that all four have failed at 40,000 miles, or could it be that something else is causing this, and Toyota are just doing an easy fix, hopeing it will sort it?

I would rather they do a thorough check on the car. I intended to keep it for around 4-5 years, so want things sorted now, (and preferably under warranty!) rather than storing up problems for the future.

Is there anything I should be asking them to check when it goes back in, (so that I sound like I know what I'm talking about!)

Any opinions would be greatfully received.

[Lizzi]

Just an update on this: The engine light stayed on after starting the car to come home. It remained on the following day for a further trip to the shops and back. Starting it up yesterday and today to go and return from work, the light has gone off, and stayed off!

Has anyone else had this intermittant problem with the check engine light???

[bestseany]

It's hard to diagnose without knowing exactly what the fault codes are that are being stored.

I find it highly unlikely that the other O2 sensors would fail because of another failing.

[Lizzi]

Can completely see your point. Think I'll have to invest in a code reader. Is there any in particular I should be looking for?

I see eBay have a selection from about £15 to £30. I don't want anything fancy - just something to take the code, so I can check what it is on google, and then perhaps clear the code?

[bestseany]

Any standard OBDII code reader should do it.

I paid £50 for mine but it's a handheld unit with a built-in code database rather than one that connects to a computer.

[Lizzi]

Just a further update on this : Toyota read the fault codes again and said it was a 3rd O2 sensor failure. They also think the ECU may be playing up, so have put in awarranty claim to have it, and the 3rd sensor replaced. They have cleared the code, and am waiting for the part to come in. So far (touch wood) the light hasn't come back on.

Does this sound reasonable, or do you think Toyota are just replacing the ECU to hope it solves the problem?

Getting paranoid about this dame light every time I start the car now.

(By the way it drives fine)

[B3rtie]

Agree with Beastseany. In my opinion the EMI light will come on because there is a problem with a component not necessarily the sensors.

Toyota dealers love to change the sensors because they are easy to fit (I went through six as they considered these to be the issue and not my cat - see my old posts) but you need to ask them what the fault codes are and diagnose from there. As the other posters have mentioned it is a DIY task to check this yourself and make a note of the codes each time. My reader came from these people www.gendan.co.uk/ (not the cheapest) and works from laptop software with a number of vehicles