Lambda Sensor

[Stevemc0]

Hi I have checked the forum for my problem but couldn't find an answear (searched for two days)

So I apologise in advance if I have missed the answear.

My problem is I have two codes that keep coming up on viagcom they are p1119 and 1118

I know these refer to the heater circuit being open or short. I have checked plugs and wiring and couldn't see any problems. I have seen on other threads that there is a box at the front of the engine (rhs) in front of battery which may have something to with the heater circuit is this correct ?

I have taken the cover off of this box and found two black wires and two red wires (thick ones) coming out of it and three fuses two are 30amp and one at 3amp the 3 amp looks like it may have blown is this fuse for the lambda sensor heater ? I don't have a manual or tis cd as yet so could some kind person please let me know what this fuse is for

Many thanks steve

[Stevemc0]

For some reason my signature didn't show up so my car details are 53 plate 2.8 v6 24 valve auto hope someone can shed some light into problem

[BrianH]

Think you will find that box is to do with the cooling fans as far as I know. I'd suspect the issue you have is a dead lambda sensor heater - you should be able to test this with a multimeter on a resistance test to tell for sure. You can use it to test your suspect fuse at the same time.

[Stevemc0]

Ok thanks for that I will have to go out and buy a multi meter and try it. Are the lambda heater expensive to replace ?

[BrianH]

It's intergrated into the sensor. Not particularly cheap. They vary from About £50 upwards.

[Stevemc0]

Ok the post cat lambda was replaced just before I brought the car so was the cat and exhaust . Wonder if he has brought a cheap/ wrong one without heater in Edited September 11, 2015 by Stevemc0

[BrianH]

More likely the pre cat sensor that's at fault than the post. Fault code should tell you which one. Can't look at the minute for you.

[Stevemc0]

I found this info on a site with vw codes

P1118 Oxygen Sensor Heater Circuit, Open Bank 1 Sensor 2

 

P1119 Oxygen Sensor Heater Circuit, Bank 2 Sensor 1 Short To Ground

Could this just be down to connectors or is there a fuse somewhere

[BrianH]

The short won't be down to the fuse - start with disconnecting the sensor, would suspect the heater side of it has shorted out (code should change to open circuit instead for that one - if it does then it would suggest to me the sensor is the source of your fault there).

 

Your best bet on the other sensor will be to find which one it is (will be the one before the cat on whichever one is bank 1) - again disconnect it and test with multimeter, hopefully someone can indicate which ones of the connectors are which circuit (usually theres 2 wires same colour, these should be the heater circuit).

 

Assuming the v6 has both sensors on both banks you have a known good one to test of each type to compare to. I don't know which bank is which physically, but if you disconnect one of the sensors and rescan you should be able to work out which one is which.

 

Out of interest is there a noticeable fault your trying to cure and if so what is it?

Edited September 11, 2015 by BrianH

[Stevemc0]

The engine management light is on and every time I clear the codes (3-4 times) these two codes keep coming back. When I brought the Galaxy the guy (private seller) had said he has replaced the lambda post cat which I can see he has done along with new exhaust from cat to rear, but he didn't have a code reader to reset fault codes. When I test drove the car it felt really smooth etc and still does drive really well apart from the management light being on and the two codes that keep coming back. I will try disconnecting one at a time on Sunday and see what results I get.

[BrianH]

Sounds sensible at least - the heaters won't make a noticable difference most of the time anyway, just when the car is warming up mainly.

 

I'd suspect from the codes that there is more than one of each sensor on the v6 - don't know for sure, but someone here should be able to advise if you find otherwise.

[Stevemc0]

I have done some searching and I think there is three sensors two pre cat one does cylinders 1,3 and 5 the other one does 2,4 and 6 and then the one post cat. If it's only the heater circuits that are at fault would the car pass an mot or would it fail due to management light being on ?

[BrianH]

is there a single cat on the v6 or two? If its one then your setup makes sense as the second one wouldn't be needed anyway.

 

On the EML light  as best I can tell no it won't - I've looked in the testers manual and cannot find mention of it - closest i could find from an official source is as follows

 

https://mattersoftesting.blog.gov.uk/common-mistakes-made-by-mot-testers/

 

https://mattersoftesting.blog.gov.uk/common-mistakes-made-by-mot-testers/#comment-5035

 

 

Incidentally the signature thing - I think you have to be logged into the forum to see it. Either that or you can't see your own.

[Stevemc0]

There is a single cat on the car just after exhaust manifold. Thanks for the information found that helpful. I think the reason I couldn't see my signature was because I was using the mobile version of the Webb page rather than full version

Many thanks for your help I will have a look at the car tomorrow once I get some time free

[Stevemc0]

I took the gal in for mot and it failed on ten items

[BrianH]

Doesn't sound too bad overall - fair bit of work done there for the money.

 

The heater only aids in the sensor response time anyway, hence why I'd asked why you were looking at it just incase you were thinking it was causing problems with more noticeable symptoms.

[Stevemc0]

No there were no other symptoms the gal runs really well it was just the management light is on and I wasn't sure if it would pass the mot with the light on. Also wasn't sure if the heaters on the lambda sensor would affect the emissions. I will fix the problem as I don't really like driving around with the management light on

[BrianH]

Possible some effect on emissions would depend a lot on the driving you do thought

[sparky Paul]

The heater is there to bring the sensor up to working temperature quickly on cold starts. The sensor may otherwise function correctly, but any fault detected may cause the ECU to revert to a failsafe running mode which ignores the sensor and runs the engine on a lean mix, to avoid damaging the cat. The lean mix is usually obvious on the emissions test, with a high lambda reading at idle, and will have an effect on fuel economy.

 

The other alternative is that the ECU continues to run happily on the information from the sensor, and the false readings on cold starts may cause damage to the cat.

 

To be honest, I would take any emissions fault seriously as a type approved cat on later cars can be expensive to replace.