Previa Engine Management Warning Light, Urgent.

[Glanma]

Hi Ray

Great to see your posts - very helpful indeed. Mine is a 2002 Estima TA-ACR30w, import obviously, on about 20,000 miles at the moment. Do you know if they are likely to suffer the same probs with the sensors and ECU as the UK ones?

Cheers Glenn

[Peter Lyons]

Ray,

We have an auto gearbox and the mechanic who fixed it said that due to poor maintenance before we owned it, the sump was completely blocked and they have therefore replaced it. The car drives ok now but of course the MIL is still on.

We are therefore looking to fix the MIL problem permanently now. In your experience, does the replacement of the Cat + Lambda Sensors + computer upgrade provide a permanent fix or is it likely to recurr after a certain number of miles?

Thanks,

Peter

PS I'm in the RAC through TOC so they picked me up from the M25 and took me home.

[Tardis]

We're now having exactly the same problems as everybody else, Engine management light on at 45k miles, 02 Previa 2.4 auto.

We had two lambda sensors replaced in May 05 (see my earlier post to this thread, first page!) but the warning light came on during our holiday Aug 06 (much stress). Initial diagnosis was 4 lambda sensors needed replacement but that sounded ridiculous so I asked for more investigation. They've now diagnosed a faulty Cat, replacement cost £807 and say that will solve the problem. The comments on here suggest it won't.

Can anyone supply contact details at Toyota UK to discuss how they will solve this? At 40k miles it would be reasonable to contribute to the cost but Catalysts are usually £200 not £800 and the usual design life is 60-100k.

I'd also be interested to know if the Cat/sensors/EMU fix is long-term successful?

This is the first Toyota I've ever bought, bought because of their reliability reputation and bought new so that I could be confident of it long term. Why aren't they sorting it out? I'm seriously disillusioned.

[Ray99]

Hi Glanma

I've not seen one but my guess would be that your Estima is a re-badged Previa. I'm assuming you have a petrol engine? I think you can look forward to similar problems.

Tardis and Peter, the fix seems to work on a long term basis. I've seen one in our dealership have a cat, 4 sensors and the ECU upgrade, and it has not returned. I usually count this as a result. The dealers who want to fit 4 sensors, then change their mind and say it's a cat haven't done the correct diagnosis procedure. There is a whole section on the technical help system devoted to diagnosing cat and emissions faults. The trouble is, most Toyotas have been so reliable for so long that we never needed to learn how to fix these kind of problems. Now of course, the problems are more frequent, technicians are having to learn how to diagnose and fix these faults.

The reason for the damage when a lambda sensor goes faulty is this:- the ECU gets the signal from the sensor, the faulty sensor is sending a faulty signal- it's saying the exhaust gas is weak, even though it's not, the ECU richens the mixture and despite the richened mixture, the sensor is still sending the faulty (weak)signal. This excess of fuel is burned in the cat and results in an increased cat temperature. Cats work best between 300 and 600 degrees C. Below this temperature, no conversion takes place, and above this temperature damage to the ceramic beds takes place. Basically they melt and the resultant liquid is deposited in the silencer. This is an extreme case, but I have seen it happen. Hence the need to replace cat and sensors and the ECU upgrade. See my earlier post for the reasons for the ECU upgrade.

With regard to the "welded" lambda sensors, I've had just one sensor strip its threads on removal. When the cats get overheated, the threads get damaged and this makes them difficult (but not impossible) to remove. The correct diagnosis procedure takes time, and time is in short supply in a Toyota workshop. The emphasis is on:- quick diagnosis, order something, even if it's wrong and get on with the next job.

We look after several Previas and looking at these posts, I would have expected to see them more often. Perhaps we don't have enough on our database. Best of luck with your various problems. Ray

[Glanma]

Cheers Ray - I think!!!!! Yes ours is a petrol, that said it does have a different ECU to the original which almost gave me problems getting it through the ESVA. I always assumed it had been changed for performance reasons but maybe there are other reasons behind the change. At least I know now what to keep an eye on in the future. Appreciate the advice. Cheers

[mobeyone]

mines on 37k now.....

Mot just done and all good...

I take the deterioation is very sudden then? i.e. there are no symptons for a failing cat?

Just booked mine in for its 40k service next month..... warranty runs out in jan 07......

Very worried.

[Tardis]

Mine had an MOT (including emissions test) and service (40K) in June. Problems happened in August, no warning.

[mobeyone]

Mine had an MOT (including emissions test) and service (40K) in June. Problems happened in August, no warning.

:(

Have toyota contributed to any of the costs?

Any other previa owners who have not had premature cat failure?

[Tardis]

Have toyota contributed to any of the costs?

Nope, apparently the fact that I imported mine (new) means that they won't contribute towards their design error. Perhaps if I'd paid their inflated UK prices then they'd have owned up.....?

[Peter Lyons]

After a lot of hard negotiating with our dealer we have just had the 4 lambda sensors replaced, a new Catalytic conveter fitted and an upgrade to the computer. The dealer has agreed to do this under warranty! I picked the car up this morning and refuelled on my way home. And then the engine light came on again!! We just spoke to the dealer and they think it's probably a loose connection that the will fix for us. I really hope so because my wife is threatening (quite understandably) to sell the Previa and buy a brand new MPV.

I'll keep you posted . . . .

[mobeyone]

Hi Peter,

I think a letter to Toyota GB is called for.

No way I would be hppy with this.

I take it you still drive the car? has there been any significant change since the new cats were put in?

cheers

p.s.

Just to let you know, my car now does around 28mpg... slower driving and averaging 350 miles before the light comes on, onboard cpmputer says 23.3 mpg. See what yours does with the new comp and cats etc.

[Peter Lyons]

Hi Mobeyone,

We still drive the car when it's not in the garage being repaired, which is not very often right now. The dealer is confident he can fix it. Apparently the light is now off but the exhaust is blowing. So we will get it back early next week. I have only dealt with our dealer and not Toyota so far. I doubt they would be very interested in my problems with a second hand car without FSH however.

From what i can tell the car drives better now with the new cat etc. But then again I only did about 5 miles before the light came on and we sent it back to the dealer!

[Ray99]

Hi Peter

I suspect the reason for the return of your MIL is because your exhaust is blowing. How does the ECU know that the exhaust is blowing? Well it doesn't, but it can measure extra oxygen in the exhaust that shouldn't be there. When you have an exhaust leak, it spits out as the exhaust gas comes by. After that pulse of gas pressure has passed, it leaves behind a negative pulse (vacuum). This sucks in fresh air with its 20% of oxygen. The oxygen sensor reports this to the ECU and on comes the MIL. Fix the exhaust leak and the problem will be go away. Regards Ray

[Peter Lyons]

Hi Ray,

We fixed the exhaust leak and unfortunately the MIL is still on! The Toyo garage then checked with our dealer to check exactly what work they had done to it before it went to Toyo. It turns out that our dealer, when they said they'd change the O2 sensors actually hadn't - ditto for the Cat. It's astonishing to me that they could behave in such a manner. But also I thought you'd all like to know that Ray's fix cannot be discounted based on our experiences. It just seems that we bought the car from a thoroughly dishonest second hand car dealership. could be a case for Trading Standards / DVLA to hear about.

Interestingly and entirely coincidentally we received a very nice letter from toyota Head Office recently advising that there is a problem with Previa engine coils overheating which can cause the MIL to come on. Serious engine damage can occur if the problem is not fixed. Toyota have fixed the coil for us free of charge.

Our Toyo dealer is now rectifying thwe work that our dealer claims to have done - and billing them for it!

[mobeyone]

Hi Ray,

We fixed the exhaust leak and unfortunately the MIL is still on! The Toyo garage then checked with our dealer to check exactly what work they had done to it before it went to Toyo. It turns out that our dealer, when they said they'd change the O2 sensors actually hadn't - ditto for the Cat. It's astonishing to me that they could behave in such a manner. But also I thought you'd all like to know that Ray's fix cannot be discounted based on our experiences. It just seems that we bought the car from a thoroughly dishonest second hand car dealership. could be a case for Trading Standards / DVLA to hear about.

Interestingly and entirely coincidentally we received a very nice letter from toyota Head Office recently advising that there is a problem with Previa engine coils overheating which can cause the MIL to come on. Serious engine damage can occur if the problem is not fixed. Toyota have fixed the coil for us free of charge.

Our Toyo dealer is now rectifying thwe work that our dealer claims to have done - and billing them for it!

Excellent result Peter!

Let us know how you get on.

Did they tell you anything more about the coils? and at what age are they most problematic? mileage etc?

[Peter Lyons]

I don't have the letter in front of me but from what I recall toyota did not mention specific mileages when problems could occur. I think it was more a matter of the year and model of the car being a problem. mine's a 2.4 CDX W-reg (2000).

We have had the car back now for nearly 24 hrs and the MIL is off (better than previous experiences!). It turns out that our 2nd hand car dealer had in fact replaced the Cat ok. However, when they said they'd changed all 4 O2 sensors, they'd only changed two. They split the cost with me for those, which at the time some months ago I considered very decent. The Toyota garage looked at the O2 sensors this week and discovered that they weren't Toyota O2 sensors, they were just some cheap old sensors. The sensors didn't fit the car properly, so our 2nd hand dealer decided to trim some of the wires and tape the O2 sensors in place! Toyota suspect that this may have caused the problems with the CAT and ECU. This is ironic really because Toyota are now billing them for the new O2 sensors, CPU and CAT. The courtesy car given to us by the 2nd hand car dealer is now with Toyota as collateral until the Toyota account for this work is settled.

This is a good result for us I think but the time we have spent arguing with our dealer and having the car in the garage (it was in for a five-week spell recently) has been trying to say the least.

Thanks to Ray for pointing out the fix. Without it, we would have had difficulty sorting this out.

[pughie]

Hi Peter and Ray,

We have had this problem since March!

First time the light came on I repalced the sensor with one from a breaker. Light came on weeks later.

Next time I took it in I was told an ECU upgrade would solve the problem, but the light came on again on the way home.

I have just had the coils done under the recall, they also replaced the CAT? Guess what the light came on again on the way home. I am taking the car back again tomorrow. Wish me luck.

Did your light come on again Peter or is your problem solved?

Paul

[Peter Lyons]

Hi Paul,

Sorry to hear you are having problems like we did. As you know, we have done the full fix now (new ECU, 4 sensors, CAT) and so far so good with our warning light. It looks like the full fix is the only way to resolve this permanently. I'll let you know if we get any problems in future.

Peter

[Peter Lyons]

The fuel consumption on the Previa is still horrendous however (about 14.5 mpg). We tend only to use the car around town and also mainly for the school run, so that may have something to do with it. I have taken to checking the tyre pressure regulalrly to see if this helps.

What is the experience of other Previa owners regarding fuel consumption?

Thanks, Peter.

[MKG]

The fuel consumption on the Previa is still horrendous however (about 14.5 mpg). We tend only to use the car around town and also mainly for the school run, so that may have something to do with it. I have taken to checking the tyre pressure regulalrly to see if this helps.

What is the experience of other Previa owners regarding fuel consumption?

Thanks, Peter.

According to the car computer, my Previa (X reg CDX) did about 35 mpg on a motorway run (South Wales to York) and does low 20s around town. I appreciate the computer may not be exact, but should give a general idea.

Had the car as an ex demo but have had the engine management light problem for a couple of years - used to go to dealer and get it reset, but just ignore it now as doesn't seem to have affected the cars performance and replacing all sensors and cat seems a bit expensive.

[pughie]

Well I'm just back from my local dealer. Guess what I need two new sensors!!!

I am going to have it done Thursday. I will keep everybody posted. I mentioned this site, and the problems everyone was having. They pretended not to know anything about it, other than needing the ECU upgrade. Which coincidently they did for me on 31/07/06.

PS I'm paying full whack as well!!!!

Paul

[Bluebottle]

Ray, thanks for all that info, it's going to prove very useful , my light came on yesterday at approx 43000 on a 02 Previa.

Local dealer (I was in sight of them when the light came on) want £57 to plug in a computer to see what's up, seems a lot to me or is that about normal?

Light went out today :)

Ours is running on LPG so I would think that the cat is a bit redundant, as long as it dosn't break up and cause a blockage. ;)

[Tardis]

I've just posted my views of Toyota's approach to dealing with this design failure on the "Toyota Owner Reviews" feedback section of their website here.

If enough people post their views then they may notice.......

[brushman]

What does updating the ECU actually do? Does it correct the fuel mixture? If you put new sensors in, will the ECU still cause the fuel mixture to be too rich or will it automatically correct itself?

Also how can you check definitively if the Cat is faulty? What are the symptoms?

Many thanks.

[chrisf]

:ffs: :ffs: :ffs: :ffs: hi ya all

Im new to this web site and i did post a long message in the other post room.i have a 53 previa with 33,000 on the clock bought last week. and the main dealer i bought it from assured me it had a full service history.however they could not find it. but they did show me a computer print out of the servicing it had had at the other main toyota dealers in sailsbury and there sure enough was a complete history. however there was an entry which said main oil light came on between the 20 and 30,000 mile service. i knew nothing of this site so thought perhaps the level had dropped or a problem with the bulb or fuse, so i bought it. it the started eating away at me so i phoned sailsbury and i spoke to the servicing dept they told me that the lady bought it in after the oil light came on and that it was making a horrible noise. and under warranty they changed the cylinder head and the short block at a cost of £7,000. i have noticed that when i lifted the bonnet there was water staining. i trused the guys when i test drove so didnt klift up the bonnet (afterall main dealers) cab, trading standards, and toyota.co.uk all say what are u moaning about u have a new engine installed by toyota but i have lost all confidence in this one and am looking at a newer one with only 10,000 on an 06 what do u guys thoink please help.

regards chris