52 Plate Lambda Gone Again

[jako999]

Hi all its been a bit since I posted but yet again our 2002 2.0 UK petrol rav has killed another heater in lambda 1. This will be the third in as many years and I am pee off the car works fine so has anyone come up with anyway of fooling the ecu yet so the light doesn't come on.

Thanks in advance

[spedo]

Hi

It seems to be a common problem with this vehicle. Before you condmn the sensor unplug it and check you have Battery voltage to the sensor. To test the Battery voltage measure at the vehicle side plug right hand pins top and bottom with the ignition on (engine not running). I did not have Battery voltage at mine so the heater could not heat. I made a tempo earth and now it works. I suspect the ECU is not seeing a current draw to the heater which is turning on the light thinking the heater element has failed. Although the sensor is working fine the light is still comming on so I need to trace where in the circuit the bad earth is. The tempo earth that I made may be in the wrong place within the circuit so I need to find the break if I am ever going to get the light to stay off. When I get the time I am going to measure the the voltage at the ECU and check the relay and associated wireing. You may also need to check the around the engine coolant temprature sensor as the voltage to the heater should turn off at around 20deg C engine temprature. If the voltage is not switching off at that temprature then this may be the reason your heater side of the sensor is wearing out as it is constantly on whist driving. This problem is a real pain as you say. If you can think of anything that happened around the time this problem started, for example, anything done to the vehicle just prior to the fault. i.e new sound systen etc, let me know, only this type of modification has been done to the vehicle I am working on which has been reported to to be around the time the fault first presented which will also need looking into.

[Joylove]

They are a bit hungry on sensors, are you fitting good quality DENSO sensors? Buy cheap, buy twice etc.

Also use your multimeter to check the coil heater resistance. Measure resistance between the two black wires. Expect~4Ohms for the top two sensors and ~15Ohms for the bottom two.

If there is infinite resistance the heater coil has indeed failed.

[jako999]

Hi thanks I spent a lot of time over the years on this problem and I am sure its an ecu error if you look at the states they have the same problem but there was an ecu remap that Toyota do free and it fixes the problems. I have had Denso and even went for a Toyota one after pulling my hair out for 6 months, I know their the same but I was getting desperate, the final fix the last time was to get hold of a second hand one that had done 40,000 miles fitted it and the fault went and it has lasted 12 months that one of the reasons I put it all down to the ecu.

Thanks again

[Joylove]

Would be interested to read the US thread about the ECU update. I wonder if Toyota UK have it.

[spedo]

Hi Jako

I do know the drivers within the ECU are known to give problems, but this is not always the case. First you need to establish if the sensors are working and or the ECU is reading from those sensors. Many vehicles require software upgrades and I like Loylove would be interested in the Toyota version number of any such software upgrade. I don't have much to do with Toyota but I do find it frustrating when it comes to getting up to date technical information. Most repair shops will throw a known good ECU at the problem and charge the customer for it even if it turns out to be bad wireing or failed sensor. The ECU is nothing more than a switch in its basic form but the switching is carried out at very high speeds from the sensorary information received. All the switching is to ground that's why it is vital that all the vehicle earth's are in good condition. I believe the ECU is either not recieving the current draw information from the heater plug or is not processing the information properly from within the ECU. You could take the glove compartment out and have a look at the the ECU connections for security and that the wires are in good order which is the first line of common sense fault finding. You could go down the same road as before and change the ECU, however this may be an expensive exercise if the fault is elsewhere on this occaision.

[jako999]

Toyota UK will say they know nothing about the free upgrades I cant tell you where I saw the info but if you hut around the net there is qite a lot about it.

THanks

[jako999]

Toyota UK will say they know nothing about the free upgrades I cant tell you where I saw the info but if you hut around the net there is qite a lot about it.

Thanks

[Julianne Kardine]

Hye there, I was reading your posts on here, I have a rav4 thats in need of a lambda sensor, but although its been pointed out which one i need I dont have a part number for it, all I know is that its on the top rh side looking under the bonnet. Sorry guys im female, crap with hoovers too! I've been led to believe its an o2 sensor and can anyone help me with a part number or where I might get a part number from ive been quotes £200 from Toyota but ive seen Bosch for about £75. Could someone please help a frustrated chick. Anything is better than nothing.

[Joylove]

http://www.toyotaownersclub.com/forums/index.php?showtopic=128709

Get Denso from World Car Parts.

[Joylove]

http://www.toyotaownersclub.com/forums/index.php?showtopic=128709

Get Denso from World Car Parts.