Engine Light on

[Mrs Bardsley]

We have a toyota yaris 2002 vvti 1.0.

I sat in it on Saturday and the engine light came on and stayed on.  Oil level is good and about where it was when I changed the oil 5k ago.  Coolant level is good.  I clean the MAS when I replace the air filter 5k ago.  The car runs nicely at higher revs but is now rough at low rev / idle.

My wife is going to get the code read but google suggest that maybe the oxygen sensor needs replacing?  Mrs said she had to drove it through some wet on the week before this happen.  I found the sensor and it is indeed near the bottom of the car and look easy to change.  I also read that sometimes is can be fuel pressure and sometimes spark plugs but the car is running well at higher revs so these don't seem like the cause?

Is the oxygen sensor often the cause of the engine light coming on?

[RUToyota]

Often, yes...the code read will confirm.

[Mrs Bardsley]

thank you.  I will report back

[Mrs Bardsley]

Mrs B got the code read and it said mis firing so that is spark plugs or leads?

[Mrs Bardsley]

spark plugs replaced by Mrs B's brother.  Problem not solved next we replace the coils

[Gerg]

There will likely be only one coil that has failed. 

The fault code will tell you which one it is.

They are commonly available from motor factors etc.

[RUToyota]

yep..Failing coil packmost likely.

[Mrs Bardsley]

thank you.  I explained this to my wife that probably only one will have failed but their brother was insistent that we replace all the coils.  He has offered to do the work so why not.  £84 for 4 coil isn't a bad price.  I'm away for work or I would be spannering.  However, he is much better mechanically than me anyway.

I would of though too that the reader would of said which coil had failed but wife was just told mis-fire 😞

I will report back when my brother in law has changed the coils. 

[RUToyota]

Ideally you should have been given the actual fault code rather than some broad comment about "misfire".

[Mrs Bardsley]

Mrs B thinks that replacing the coils has sorted this.  The faults are still there but I guess they need to be cleared by a reader.

She did mention that it was better at idle but still not as good as before.  I think there might be more to do but lets see.

[stantheman1]

Check for vacuum leaks.

[neilbardsley]

Problem still present.  Codes not read again yet but mechanical niece is now guessing the timing belt or compression.

Seems really strange as these engines are normally super solid.  It only has 69k on it.  I changed the oil once I got it and it had a service history.

Hopefully it's the timing belt

[stantheman1]

No timing belt it uses a chain and highly unlikely that this is your problem.

Do you have any carb cleaner to hand?

[neilbardsley]

Sorry I meant to type timing chain.  I was surprised to here her suggest the chain was an issue?

Yes I do have some carb cleaner.  Where should I clean?  When I got the car I put some injector cleaner in the petrol.

Any chance the fuel filter needs changing?

[stantheman1]

As others have enquired "what is the actual fault code"?

The carb cleaner is for checking for vacuum leaks that are not clearly visible, vacuum leaks can cause the engine to run poor at idle, a quick and simple way to check is to spray carb cleaner around and along the vacuum hoses/pipes and if there's a change in idle speed means you've located the loose or broken line. 

[neilbardsley]

Ok I will check that now.  Compression test results are 14, 13, 12, 11.3.  I hoped they would be closer together but they are pretty good numbers

[neilbardsley]

Idle reacts to cleaner being sprayed at air manifold 3.  I used to working on cars with carbs so I assume this is the air in?  What I'm calling no 1 cylinder.  I'm going right to left when facing the Engine

[stantheman1]

I would call that no. 4 cylinder.

Can you see any cracks in the plastic inlet manifold? Also what are you showing us in the picture?

[neilbardsley]

I can't see if there are cracks in the manifold.

That I was trying to saw in the picture was one of the manifolds

[neilbardsley]

I didn't realize the manifolds were all one piece.  Plus the gasket is one gasket for all four.  It's going into a garage this Tuesday but I had a Google and couldn't find and new manifolds for sale??

[stantheman1]

It may be that it's just the gasket that' s leaking but you'll soon find out once it's removed, eBay have a few pre owned ones for sale! Thanks for posting and please update us with your findings.

[neilbardsley]

When into a garage and it was a vacuum leak they repaired. 3/4 labour but Mrs B picked it up so no more details.  Car idling nicely again

[stantheman1]

That's what i suspected all along! (#11)

Thanks for posting back your solution which could help others in the future when using the search function. 👍

[flash22]

Glad you got it sorted

As a rule No.1 is the end with the crank pulley/fan/aux belt and 4 is at the gearbox end (inline 3,4,5 and 6-cylinder engines) but there always an exception to that rule