Gen 7 Celica Hydualic Tensionners And P0420

[bod]

Hi All,

I've been watching the forums since I bought my Celica Gen7 back in February. I’ve got something that you guys and gals can help me with.

I have a 2000/W 140 with 70k on the clock. I bought it 6 months ago and I have done 10k in that time and it has been a dream to drive until recently…

I have noticed that on damp/wet mornings the aux-belt squeals until the vehicle has warmed up and I have an intermittent P0420 fault. (I bought a hand diagnostics tool on eBay and reset it when it comes on about every 500miles)

I’ve just had the 8th full service at Toyota (Kings Winchester) for a wallet-hurting £270 and the garage offered to “check” any other niggles for free. I asked them to diagnose the squeally aux-belt and the P0420. They duly did this for me informing me that the hydraulic tensionner leaking fluid caused the squealing and that the P0420 was caused by both the O2 and lamda sensor being knackered. They also told me I needed 2 new front tyres. The total bill including the service would have been £1185. As you can guess, I politely told them not to worry. They quoted me £285 for the tensionner and £460 for the sensors (inclusive) and £170 for the tyres.

My local mechanic wasn’t much more helpful saying that he wouldn’t advise OEM sensors on a VVTi and the he’s never done a tensionner before so it’ll cost however long it takes.

I have a couple of questions that you ladies and gents might be able to help me with…

Thanks to Jaxx for his link to oxygensensors.com and I have bought an O2 sensor for a Vectra from gendan.co.uk before so I know they're a good company.

Can I use OEM sensors?

I think it’s the 4 wire I need, can anyone confirm this?

Toyota said that tensionners have been known to go on the VVTi, anyone else had this problem? How much and how did you fix it?

I wish I bought the 190 as well.

I know you're all busy and should be working (like me) but your combined wisdom is appreciated...

Matt

[bod]

Back again...

I've clarified the Sensor issue with a little help from http://www.justlambda.co.uk/ and http://www.gendan.co.uk (Thanks!)

I crawled under mine and it has 4 wires: black,black,blue,white -which appears to work with a compatible universal sensor.

i'm going to get the Zirconia 4-wire sensor from Gendan because they're cheaper and they should be able to get them to me tomorrow!

[bod]

I have an important amendment to the above.

The universal sensors DO NOT work correctly without a modification. I think as the GEN7s get older more of you will be doing this DIY job to save yourselfs a few hundred quid... (remember it's £150 a sensor from Toyota!)

If you connect the universal sensor to the loom without the mod then you will receive MIL code P0135 & P0140. They can be diagnosed as a heater circuit fault on the O2 sensor and Lambda sensor respectively.

I would like to thank Grant Norman of Gendan for the following information:

We do not recommend fitting universal Zirconia sensors to certain Toyota

cars. Toyota tend to use unusual heater resistances and fitting a universal

sensor can cause the ECU to record a heater sensor fault; this appears to be

the problem you are experiencing.

Indeed he is correct the heater resistance of the Zirconia is about 4.3ohms and the Toyota sensor is about 13ohms. The ECU is clearly confused and reports an error, it is worth noting that the error only occurs when it is cold and, if reset when warm, does not reoccur.

I took some technical advice and ascertained that a W21 vitreous wirewound resistor, 10R 2.5W would suffice. These can be sourced from RS:

http://rswww.com/cgi-bin/bv/rswww/searchBr...amp;Ntt=152-303

All you need to do is solder these inline with one of the heater wires (black on the car / white on the sensor) and reset the ECU error code and everything will be good again.

I hope this helps some other GEN7 owners make a decision about how they fix their sensors.

[VVTLIProbe]

I didn't realise about the 13ohm value. At least if similar sensors are purchased at least members now konw to take the difference from the 13ohm then purchase resistor to match.

This is also a similar match to the decat MIL eliminator when the CAT is taken out and the ECU thows up the CEL, the MIL uses a resistor inline + capacitor in parallel to create a test signal as to fool the ECU that the CAT is still present.

1MFD Capacitor

1MEG 1/4 W Resistor

Step one:- Sever the Blue wire and bridge them back together using 1meg 1/4 W Resistor

Step two:- Splice the White wire (do not cut) and bridge it with the Blue wire. Make sure you bridge

the blue and white wire before the Capacitor coming from the ECU.

[Black Knight]

Well considering to change the tensioner requires removing the belt and then undoing 2 bolts I can't see how it costs £285. One bolts pretty long and might cause a clearance problem to get out since I can't remember what's to the side of it.

Sketch the belt route for future reference

Use a 19mm (I think) spanner on the welded hex to take the tension off the belt and remove it.

There's then one nut at the top of the tensioner and one bolt about half way down it.

Undo them and it comes straight off

Reverse to refit

As i say check the clearance to the side since one of the bolts is pretty long and might be awkward to remove.

[bod]

Hi Black Knight,

Thanks for the reply. I agree £285 is a lot but i've always been quite wary about my ability to wreck my car.

Toyota quoted £39.16 for the belt and £115.92 for the tensionner. :censor: I guess £130 is reasonable for a couple of hours of dealers rates but still a lot of money for a simpleish job.

Subsequent to your message I took off the engine cover and had a poke around. I'm not sure I know which one the tensionner is. I can find the Alternator, A/C Pump, Coolant Pump, Power Steering and bottom drive pulley wheel. There are two others that could in theory tension the belt. I guess if I buy the unit, i'll be able to figure out which one it is?

Before I go out and spend £155 on parts, does anyone know anywhere I can buy a cheaper belt/tensionner?

Either way, I'll document my findings for future generations B)

[Black Knight]

http://www.absoluteingenuity.net/matrix/re...eg/1zzfeser.pdf

Belt tensioner unit is the bit going up left from the idler pulley for belt tensioner

[Timmy190]

Bod,

I've got a 2000 Celica 190 import, and have exactly the same problem with the auxilary drive belt and have had now for the last 8 months, I was actually looking on here in the hope of finding other people with the same problem that have managed to fix it.

It started on my car with simply as if the auxilary belt was slipping and needed replacing, I took it to the garage and they agreed, I had a new belt fitted, problem didn't go away, the toyota dealer then looked into the problem with Toyota technical centre and found out there was a modified belt to cure this 'known' problem, that belt was fitted but didn't cure the problem, they then identified a modified tensioner unit, which was then also fitted, the problem was better but not cured.

I've since had 2 modified tensioner units, 3 belts, the garage has even rebuilt the air conditioning pump, and replaced both the water pump & power steering pump, but it has made no difference.

The last time I spoke to the toyota dealer they said Toyota were close to putting it to one side and calling it a design fault. The problem is toyota do not warrant these anymore and as such aren't interested in trying to cure this problem. Which is so annoying as it is a fantastic car otherwise.

[bod]

Black Knight: Thanks again, the link is great and there are also some other useful PDFs there.

Does anyone know where to get wiring diagrams and stuff specifically for the Gen7 Celica? Would be useful considering Haynes don't make a manual.

Timmy190: Hopefully mine is a simple fix - it started squealing a few months ago in damp/wet conditions and went away when the engine warmed up. I was thinking of changing the belt but then I had Toyota check it on the rountine service; they said the automatic tensionner was leaking and not tensionning properly. I guess this replacement is the first avenue for me to try.

If it is a 'design fault' then it'll be the excuse I need to trade it in for a newer 190...

[bod]

I thought I'd update on the final outcome and a guide on how to do it. My squealing problem has been resolved by changing the belt and tensioner. There was evidence of hydraulic fluid on the side of the engine as well.

A bit more challenging than it looked, mainly because of stupid design. The bolt holding the tensioner on is actually too long to come cleaning out the side before it hits the wheelarch.

** I ACCEPT NO RESPONSIBILITY IF YOU BREAK YOURSELF OR YOUR CAR DOING THIS**

Tools needed:

M19 Socket (Shallow) and long bar

M17 open ended and ring spanners + extention bar of some sort (very stiff to undo otherwise)

M12 Socket (or Spanner)

M14 Socket

E8 Torx Socket

Flatbladed Screwdriver

Trolley jack

Light/Torch

About 1-2hours and possibly some assistance.

IMPORTANT: Make a note of the belt route or print out this link

http://www.absoluteingenuity.net/matrix/re...eg/1zzfeser.pdf

Remove the Plastic engine cover by popping out the clips. You may break these but they're cheap. You may want to remover the rocket cover as well.

Release belt by using the M19 Socket and bar on the conveniently placed bolt. Gently release the tension in 2 or 3 slow movements. Pulling too hard or too quickly can damage the hydraulic tensioner (oh, never mind)

Flip the belt off the alternator (or ask your assistant to do so). Release the tensioner and then pull the belt away from the other pulley wheels.

Release the M17 Bolt on the tensioner, mine was very stiff and needed some "gentle" persuasion. Release the bolt as far as possible - it will hit the wheelarch and will not come away yet.

Release & remove the M12 Nut on the top of the tensioner. Using the E8 Torx socket losen the shaft that holds the top of the tensioner on.

Here's the fun bit. Assuming you can't get the M17 Bolt or shaft out you'll need to jack up the engine. If your car is like mine the engine won't shift at all, so you need to release the engine mount.

jack up the engine just enough to take the weight (i used a large trolly jack on the sump - not sure if this is recommended). There are 3x M14 bolts that hold the left engine mount in place. 2 are obvious and 1 is hiding behind the power steering fluid resevoir. The PAS resevoir can be moved by releasing the clip on the back with a flat bladed screwdriver. Release the bolts slowly in turn it may not come away straight away. Once they are all clear jack the engine up and the mount should come away as the engine rises. Jack it enough until the M19 bolt and E8 torx shaft can be removed.

It takes some wiggling and a bit of innovative thinking but the whole assembly will slide off and you should be able to work it out.

Refitting is reversal of removal...

Slot the shaft into the top of the tensioner and slot the M17 bolt into the tensioner. Work them back into place and tighten in the M19 bolt and E8 shaft so that they are supporting the tensioner. Slowly release the jack so that the engine mounts line back up. Insert the engine mount bolts in turn. Your assistant may have to hold the mount in place while you line them up. Tighten them in turn. Re-clip in the PAS resevoir into place.

Tighten up the E8 Torx shaft. Put the M12 Nut back on. Tighten up the M17 Bolt and the M12 nut.

Loop the belt back on using the diagram up top. Get it in place so that the alternator is the only unconnected pulley-wheel. Get your assistant to release the tension - do this slowly and in a few gentle strokes before releasing to avoid damaging your expensive new tensioner. Hook the the belt around the alternator. Before your assistant releases the tensioner check that the belt is cleanly looping around all the pulley-wheels and that is slotting into the grooves. Release the socket.

Check all your nuts and bolts are tight. Check your tools are clear of the belt. Check the belt again to make sure everything is where it should be.

Start the engine.

[Timmy190]

Bod, I hope this has worked for you, and I would ask that in a few days / weeks that you confirm that you haven't had the problem reappear.

As I said in my first post, I have had three new tensioner units now and with two of them the noise went away after fitting, but however started to come back within the next week or two.

Seriously though I hope this doesn't happen with yours, as I know it annoys the h*ll out of me.

[rf76]

Another thing to remember is to 'prime' the tensioner once fitted to the engine. If its a genuine Toyota part, there is a leaflet inside the box that advises the fitter to pull back on the tensioner several times via the adjuster to evacuate any air in the hydraulic tensioner assembly. If this is not done, it may start squealing again from the belts after a few thousand miles due to inadequate tensioning.

[Black Knight]

A bit more challenging than it looked, mainly because of stupid design. The bolt holding the tensioner on is actually too long to come cleaning out the side before it hits the wheelarch.

Answers my suspicion about it fouling something

Hope it saved a few quid in the end?

[bod]

Hi all,

So far so good. Done about 1300miles with a few "wet" starts and long journeys in the rain.

Seriously though I hope this doesn't happen with yours, as I know it annoys the h*ll out of me.

I think this is the first time in 75,000miles and I don't intend to own it long enough to worry about it again.

Another thing to remember is to 'prime' the tensioner once fitted to the engine. If its a genuine Toyota part, there is a leaflet inside the box that advises the fitter to pull back on the tensioner several times via the adjuster to evacuate any air in the hydraulic tensioner assembly.

Yes it does and yes I did... forgot to mention that in the guide.

Answers my suspicion about it fouling something

Hope it saved a few quid in the end?

Judging by the labour hours they were charging (we think about 2) I can imagine they do something similar to how I did it to get around the problem. Estimated saving is about £150.

Still having problems with the sensors. Getting a bit p*ssed off now. After a long journey I restarted and made a short journey and the MIL light came on with errors 0171 0130 0133 0136... seems like one of the O2 sensor is still malfunctioning. I'm going to get it up on the ramps and have a poke around.

[bod]

Right well. All sensor connections still intact underneath.

IT seems that P0171 has various causes. Some say O2 sensor can cause, some say MAF sensor, some say air intake leak. The engine obviously isn't running lean because the exhaust and sensors are thick with black deposits and it's doing 20mpg. I've cleaned the MAF sensor although it looked clean.

I can only think that changing to genunine Toyota sensors (at cost of £300) is the only answer. Anyone PLEASE have a cheaper answer that I can try? I'm going to take Monday off work and get it sorted, I can't risk driving it and damaging other components.

Once i've done that I'm then selling the car - i've just lost all faith in it and it's barely 6 years old.

[bod]

This is a follow up e-mail from one I sent to a very helpful guy at Gendan Ltd. (The supplier of Oxygen sensors, diagnostic tools and the like)

Matt,

Thank you for your email. I am sorry to hear that you are still having

problems with your car.

According to the information we have available, the OE front lambda sensor

seems to be of standard Zirconia design except from the heater resistance.

The only thought that comes to mind is that the increased resistance of wire

joins on the sensor signal line may trigger occasional fault codes. We have

found problems in the past, for example on Rover MEMS ECU's, where the ECU

is incredibly sensitive to any change in wire resistances; universal sensors

cannot be used on these cars and a direct-fit part must be fitted.

Are the wire joins soldered? If not I recommend soldering the joints with

silver solder to minimise any resistance in the wire joins.

Before replacing your MAF it may be worth checking if you can clean the

sensing element. On most MAF sensors you can gently spray carburettor

cleaner through the MAF to clean off any carbon deposits. A much cheaper

option than purchasing a new MAF. Be careful not to damage the sensing

element inside the MAF pipe.

Do you have the original sensor that you removed from the front of the car?

The P0420 fault code you had read by Toyota tends to point towards the rear

sensor. Is it possible to try refitting the original front sensor to see if

this cures the problem?

I look forward to hearing from you.

Best regards,

Grant Norman.

Gendan Limited

http://www.gendan.co.uk

http://www.gendandirect.co.uk

Tel: 08700 420 928

Fax: 01792 232383

[bod]

I swapped out the O2 sensor for a genuine Toyota part (at £154.00) and it seems to have gone away. I am not sure if the faulty sensor was the cause or a result of another problem so I am going to do some further laptop tests.

Thanks for all the advice that has been given.