Engine Warning Light

[princess]

Amber engine warning light came on in my W reg Yaris a couple of days ago. Panicked (I'm a girl!) and called RAC who came out and hooked up the computer and fault PO171 came up - System too lean. RAC man cleared the fault and said if the light comes on again to get it looked at. Light came back on today.

Called Toyota dealers and they will charge £53 just to find the fault, never mind how much to repair. Since it's not been serviced by Toyota previously should I just take it to my mechanic to see if he can find the problem? Any ideas what it might be? It was MOTd and serviced 2 weeks ago including new spark plugs, new brake pads and new suspension whatever-it-is.

Or any ideas where else I could take it? I don't want to spend a fortune getting this sorted, the whole point of buying a Toyota was that they aren't supposed to go wrong!

[Lenry]

Hello and welcome,

If I was in your situation I would take it back to the place you got it MOTed.

Then say that the MIL Light has come on since the time thay did work on the car.

is it possible they do a free check to see if the work carried out by them is causing the problem.

If not, a good garage will be able to tell you at a lower price than Toyota I bet!!

good luck!

[blue-baby]

Thats a common problem on yaris..that code is fuel trim too lean. Way we sort it is to use fuel cleaner through the engine.First off, get the code cleared so it isnt on the dash anymore. Use 2 bottles of cleaner. Put 1 straight into the tank and put 1 through the engine. Find the vacuum line going into the inlet manifold and put the pipe into the bottle of fuel cleaner.Rev the car and the cleaner will get sooked in,the car will try to bog down so keep the revs up at this point. After a short while white smoke will start to come out the exhaust,this means its all working. TONS and tons and tons of white smoke will start to come out after another while. Once the bottle is empty put the vacuum pipe back on and go for a drive,you need to drive the car pretty hard, keep the revs up high.Drive it like you stole it basically.Give it a decent 15 minute run, then let it idle for a wee while to cool down.

EML shouldnt come back on after that,if it does then your probebly looking at an o2 sensor.Only rare cases have returned after the fuel cleaner treatment has been added.

Dirt collects in the injectors and fuel rail and effectivly leans the fuel delivery.Thats what the cleaner "cleans" lol

Hope this helps.

[Moffmo]

<Snip>

Excellent post

Will remember that!

[princess]

Thats a common problem on yaris..that code is fuel trim too lean. Way we sort it is to use fuel cleaner through the engine.First off, get the code cleared so it isnt on the dash anymore. Use 2 bottles of cleaner. Put 1 straight into the tank and put 1 through the engine. Find the vacuum line going into the inlet manifold and put the pipe into the bottle of fuel cleaner.Rev the car and the cleaner will get sooked in,the car will try to bog down so keep the revs up at this point. After a short while white smoke will start to come out the exhaust,this means its all working. TONS and tons and tons of white smoke will start to come out after another while. Once the bottle is empty put the vacuum pipe back on and go for a drive,you need to drive the car pretty hard, keep the revs up high.Drive it like you stole it basically.Give it a decent 15 minute run, then let it idle for a wee while to cool down.

EML shouldnt come back on after that,if it does then your probebly looking at an o2 sensor.Only rare cases have returned after the fuel cleaner treatment has been added.

Dirt collects in the injectors and fuel rail and effectivly leans the fuel delivery.Thats what the cleaner "cleans" lol

Hope this helps.

Thanks for that blue-baby! I'll take it back to my mechanic and get him to do this, but I'll stick around to do the 15 min run - that's the fun part! :D

[seveer unaek]

You can buy a product called '10k boost' from Halfords at about a tenner that does the same thing... very easy to use and very effective.

You should also try cleaning your MAF sensor... it's bolted to the airbox... bit of compressed air or solvent cleaner does the trick.

[Lenry]

yeah what blue-baby said :D

[blue-baby]

I try my best B) Not bad for a "girl" ehh?

[Black Knight]

Other option is the Air flow meter beginning to burn out. As they go they tend to lean the mixture up which then throws a fault as the O2 sensor picks it up

[princess]

Does it matter how much petrol is in the tank when I do the clean?

And don't suppose anyone can recommend a good mechanic in North London who specialises in Toyotas?

Cheers :D

[homershairdo]

Does it matter how much petrol is in the tank when I do the clean?

And don't suppose anyone can recommend a good mechanic in North London who specialises in Toyotas?

Cheers :D

Hi

Did you get this sorted in the end - I have the same problem!! How long can you drive around with this error, as I can't get to a garage for a couple of days!

Cheers!!