Previa Engine Management Warning Light, Urgent.

[AllanH]

I found this site by accident. I was amazed to find how many others had had this problem with EMW light. My Previa GLS (March 01) developed it at about 40,000 miles. As this was at about 2 1/2 years the catalytic converter (+/- sensors, I'm not sure) was replaced under warranty. At about 70,000 miles (4 years, and out of warranty) it all started over again. Curiously my light sometimes goes off after long motorway trips, and it went off during a recent trip to France using French petrol, only to come back on when run again on UK petrol! It is currently out again after trying fuel system cleaner in petrol.

I agree with those who say that there should be som sort of "class action" against Toyota as all of us face problems selling/trading in our cars if the EMW light happens to be on at the wrong time.

[123]

I have new style toyota previa, done 80,000 miles. About half a year ago the little engine warning light came on, we took it to our dealer who said there was nothing wrong and turned it off. It has come back on and been turned off many times with no problem found. Now we have come to sell the car and really need light off, the main dealer said they had new software in to update the EMS but i would like to know what is causing this problem, any help would b greatly appreciated.

Thanks

well what it is is that the engine ecu software has a problem and there is a update out for the software which can only be done by your dealer principle by doing the upgrade on the engine ecu you would also have to replace the catalytic converter as the ceramic would have broke down inside exhaust it's been modified

[mobeyone]

I am worried.

I have just bought an 02 previa 2.4 cdx from a toyota dealer with 28k on the clock.

What do i need to do to ensure that i do not have any of the problems mentioned? is there anything i can say to them?

all advice would be appreciated.

[Juiced]

I am worried.

I have just bought an 02 previa 2.4 cdx from a toyota dealer with 28k on the clock.

What do i need to do to ensure that i do not have any of the problems mentioned? is there anything i can say to them?

"Stop laughing at me and wipe the grin off yer face!"

[mobeyone]

"Stop laughing at me and wipe the grin off yer face!"

was wondering why they wanted me to sign to quickly! :ffs:

but please guys - are there any known independants in the northwest who specialise in toyota and can diagnose any premature cat failures? I have a 30 day trial which i will be giving the car a thorough test and will take to a number of mechanics to find faults.

How do people find the braking off the previa? i noticed an uneven type feeling when braking? kinda like the abs is on as soon as i hit the pedal?

[Juiced]

The brake discs are probably a little rusty or maybe need to be machined. It was the first thing I noticed in mine and i dont believe it has ABS.

A mechanic can easily verify that for you.

as for the cat question, i really dont know... but.. this cat problem is well known so I think the dealer should just swap it out. Best of luck on that.

[Almufasa]

Further to my previous post in August 2005 you may be interested to read my log of when my engine warning light has been on and off - I kept a log to try and see some sort of pattern but it's most likely random - maybe there is a link with the weather? Also I tried using BP Ultimate petrol but that has made no difference.

Any way - here is the record - going back in time:

It's off at the moment!!

3 Feb 2006 - off

22 Jan 2006 - on

20 Jan - 2006 - off

1 Jan 2006 - on

30 Dec 2005 - off (after new Battery fitted)

21 Dec 2005 - on

12 Dec 2005 - off

2 Dec 2005 - on

1 Dec 2005 - off

14 Nov 2005 - on

3 Nov 2005 - off

9 Oct 2005 - on

1 Oct 2005 - off

24 Sep 2005 - on

16 Sep 2005 - off

15 Sep 2005 - on

7 Sep 2005 - off

[DannyM]

I have new style toyota previa, done 80,000 miles. About half a year ago the little engine warning light came on, we took it to our dealer who said there was nothing wrong and turned it off. It has come back on and been turned off many times with no problem found. Now we have come to sell the car and really need light off, the main dealer said they had new software in to update the EMS but i would like to know what is causing this problem, any help would b greatly appreciated.

Thanks

[DannyM]

Hi All

I have a Granvia 3.0L Diesel, which has recently started the flickering warning light, Toyota have put their diagnostic tool on it & said nothing appears to be wrong,however,the auto box doesnt seem to change as it did(holding back) and has now blown the AM2(engine management) fuse twice within 2 weeks.

Toyota have said when something goes wrong then they can fix it, my wife left the toyota centre and broke down on a busy roundabout with children onboard, having to offload them onto the roundabout until recovery arrived, Toyota still say nothing appears to be wrong !!!!!

My Remedy for this problem can only be to change to a reliable brand of vehicle, after loving this one to bits.

Someone somewhere must have a cure for this problem !!!

Danny

[Uncle Bob]

The weekly motoring magazine Auto Express ( www.autoexpress.co.uk ) are always interested in motoring problem and quite often ask car companies to explain them selves.

If you guys start to Email the magazine in large numbers they may take up the case :) .

Here is a list of AutoExpress contacts....

http://www.autoexpress.co.uk/website/?ae_data/contact_us/

[Peter Lyons]

I recently bought a 2000 Previa CDX. Previously I bought a Corolla in '98 and have only really had to replace the Battery and a couple of tyres over the last 8 years and was expecting similar reliability from my Previa. So I was a bit surprised when the Engine Management Warning Light came on 3 weeks after i had bought it! The rev counter was also behaving a bit strangely, dropping to about 500 revs when idling, sounding as though it was going to cut out, and then zooming up to abut 900 revs. Fuel economy was also appaling at about 13-15 MPG. Living in London I had expected poor mpg from it, but 13-15 was a nasty shock.

So I searched the net and found this forum and saw all the talk about Lambda sensors etc. and took it down to my (non-Toyota) dealer. I got it back yesterday and he had replaced two of the Lambda sensors. The idle speed is now a constant 700 rpm and the EMWL is now off. It looks like the problem may be solved for now, but judging from previous posts, time will only tell.

I'll keep you updated . . . . .

[Uncle Bob]

Hi Peter and welcome to the TOC :) , like you say, fingers crossed your problems are now fixed .

[Peter Lyons]

Thanks Bob.

Guess what though? The engine warning light came on less than 24 hours after I got the car back from the garage. And the mpg? Not looking good!

So it's back to trawling this site and calling my local Toyo workshop for advice

[Alan Harrison]

Peter, are you getting your mpg from the trip computer or working it out from your mileage. I've found the computer to be inaccurate

Alan

[Peter Lyons]

Peter, are you getting your mpg from the trip computer or working it out from your mileage. I've found the computer to be inaccurate

Alan

Hi Alan,

Thanks for the tip. Actually I assumed the computer would be inaccurate so I simply set the trip meter and did a manual calculation. I have been doing 14.5 mpg in town recently!!

On a more positive note I had one of the lambda sensors changed a couple of days ago and the emwl is off - at least for the time being. I'll keep you posted.

Peter

[mobeyone]

Mines on 34000 and getting closer and closer to the 40k mark where this seems to start...

Just to give you an idea, takes me around 60 litres a go to refuel and i average around 24-25 mpg. Usually get around 320 miles to a full tank. This has gone down lately with the increased use of aircon but it usually good for it.

My dealer is a joke, I had to battle tooth and nail to get them to do some jobs which should have been sorted before i bought the car so needless to say that I will not get any joy from them if this happens to me. The attitude of my local dealer is nothing short of disgraceful and I have no confidence in them should this problem arise.

Incidently, my car has just been though a MOT and I asked them to give the cats a very good check and they came back near perfect and he said no problems here.

Just wondering when you would expect to see the cat deterioarting? would it be a slow progress or would it be very sudden?

I use this site to do a quick calc of my fuel consumption.

http://www.torquecars.co.uk/Tuning/uk-mpg-calculator.php

Peter - what mileage did you buy your previa on? did it come with fsh? and is it under warranty? A number of online sites state that the previa is normally bullet proof?

[Peter Lyons]

Mobeyone, I bought the Previa at 80,000 miles because my previous experience of Toyotas is, like you say, that they're built like tanks. I bought it from a local second hand car dealership, with a warranty, but not a FSH. In fact, there was very little SH which should have set the alarm bells ringing really.

As stated in my previous post, they changed a faulty lambda sensor over for me last week, but the emwl is back on now . . . Grrr! The dealership is doing some work on it under warranty but i suspect they are doing it on the cheap and I am starting to wonder whether i would be better off taking it to a Toyo dealership to see if they can get to the bottom of it. Alternatively i could just invest in some sticky black tape and tape up the faulty sensors. Seems like others eventually went down this route.

Peter

PS thanks for the good mpg-calculator tool.

[jpegbj]

I have an 03 2.4 and the light first came on in France in March last year at 30,000 miles - took it to a dealer near Geneva - he turned it off, came back on again on same stretch of road 4 days later and stayed on for 10 days until the day before it was due in to the UK dealer. Came on again after a thunderstorm just 2 months out of warranty and they wanted to replcae sensors and cat for £1700 - ended up just doing sensors (all 4) at £235 with both garage and Toyota "helping" keep costs down. Came on again after another thunderstorm and stayed on for a week until there was ......another thunderstorm when it magically went off. Car is at 43,000 miles now and I guess I will live with it....

[Ray99]

Hi you Previa owners. I'm a Toyota technician and I can give you all some help with understanding what's going on with your Previas. To understand the MIL ( Malfunction Indicator Light) we need to start with the way the ECU (Engine Control Unit) controls the emissions. When the engine is up to operating temperature, the ECU is looking for a signal from the pre-cat sensors. The sensors are sensitive to oxygen in the exhaust gas. If there is oxygen above a certain level, the ECU richens the mixture until the oxygen level starts to fall. When the oxygen has fallen below a certain level, the ECU starts to weaken the mixture and the oxygen level starts to rise and the cycle starts again. All this happens several times per second at cruising speed and makes the exhaust gas look as if it is stable in its gas content. The mixture is ocillating either side of the perfect ratio, but by so little that it is difficult to measure. Two sensors are used to give finer control of the emissions. Cylinders 1 and 4 share sensor 1, bank 1. Cylinders 2 and 3 share sensor 1, bank 2. These two sensors monitor the mixture strength as the exhaust gas goes into the cat. The other two sensors- sensor 2, bank 1, and sensor 2, bank 2, monitor the exhaust gas before it is released to the atmosphere. This is a requirement now for a Euro 4 engine. If these two post cat sensors detect any oxygen in the exhaust, the ECU assumes that the cat isn't working and lights the MIL. However, under certain circumstances, usually on a long motorway trip at a steady throttle, the ECU will see variations in the signals from the post cat sensors that are normal, but a little larger that expected. The ECU lights the MIL and you come and see us. The original fix was to reprogram the ECU and allow the larger signals, before the ECU decides there is a cat fault. We also discovered that cats were indeed breaking up and sensors were giving faulty signals. So the complete fix was- reprogram ECU, replace cat and all 4 sensors. You can have your MIL on and still pass the MOT emissions test.

Previas also suffer from an unusual fault with the MAP sensor. There is a small diameter vacuum pipe from the inlet manifold to the sensor on the left hand inner wing/chassis area. This pipe has been known to fill with oil and gives hesitation and high fuel consumption. Not all Previas suffer, but worth checking if you have unexpained high fuel consumption. Sorry this has been a very long and wordy post- especially for a first post, but I felt it was worth taking the time to expain

Regards Ray

[Uncle Bob]

Great bit of technical input Ray, i can see you as being the main man to contact in the future .

[Peter Lyons]

Hi Ray,

Thanks very much for the detailed answer. We are currently disputing what needs to be done with our dealer to rectify this. Now we have some concrete information to present to them!

Cheers,

Peter

[mobeyone]

Cheers Ray, re the MAP sensor, at what mileage are these likely to fail?

I used to have a mercedes c320 which were notorious for failing MAF sensors and had mine replaced on 65k.

Anything else you can tell us on what to look out for with the new shape previa?

[Ray99]

Hi Mobey

The sensor itself doesn't fail, just the vacuum pipe to it fills with oil. I've seen two like it probably around 40-60k.

Watch out for worn discs usually on the front and usually autos. Any Previa with water/rust stains around the radiator/pressure cap area should be avoided. It usually means they have been overheated. Keep up on coolant changes, can't stress this highly enough. One overheat usually means the headgasket is destroyed. Two or more and you are looking at a cracked head. Few owners take any notice of an overheat, they prefer to top up and carry on. Hence the cracked heads. Any warning lights on- ABS or MIL look for bits of tape stuck over the symbol also bulbs removed. Buy them if you want, but be prepared for trouble.

Regards Ray

[Peter Lyons]

Hello Ray,

We have recently had 2 lambda sensors replaced and also had the MAP filter cleaned on our Prev. The car initially responded quite well to this. I took it on a 300-mile trip to Bristol and back and it was purring. Took me about 1/2 a tank to cover 260 miles and it cruised effortlessly at 70-80. Then I hit the M25 and whilst going along in the outside lane in heavy traffic I lost all traction! The engine revved and revved but it was like the gears hadn't engaged and I was slowly grinding to a halt. So I indicated left and pulled over sharpish into the hard shoulder where I came to a stop. Fortunately the other drivers could see I was in trouble and let me in before I came to a complete standstill in lane 3 of the M25. Oh yes, and following all this unproductive revving the emwl decided it was time to come on again. Grrr.

We are now thinking of having the complete fix done (2 more lambda senbsors, new Cat and computer upgrade) the cost of which our dealer will probably share. But does this fix the emwl problem for good or is it likely to start playing up again in near future? Please let me know of your experience with Previas after the full upgrade.

Plan B is to patch it up and just trade the thing in.

[Ray99]

Hi Peter, sorry to hear your Previa is unwell again. Do you have manual or auto gearbox? If you have a manual, it sounds like your clutch has worn out- slipping. If you have an auto then it's a very different scenario. Trouble is, I can't think of any situation where a slipping transmission, manual or auto, would bring on the MIL. How did you get home? Did you get a tow? Or perhaps after a short wait you had drive again? I'd be interested to know.