I think the Lamda sensor on my car maybe faulty.

From a full tank i only get around 160 miles. Can a faulty lamda sensor really afftect mpg this badly?

Sometimes, on cold mornings, when i start it up, the car runs lumpy - like it's on 3 cylinders. Floor it and boucne it off the limiter a few times and it seems to sort itself.

Anyone had a similar problem? Or can any teccies tell me if the lamda could affect mpg so badly?

 

yes

 

to that extent?

I mean 160 miles from a full tank as opposed to like 250?

 

If the Lambda is faulty the ECU will run fuelling based on the fuel base map, which will be richer then running with Lambda control.

This will be effective during idle and cruise.

 

Yes, mine did. Now it's better, but still only getting around 220 on a tank. You never by an impreza for economy

 

would any of you gents be kind enough to tell me the cheapest place to get a new sensor from? Can i fit it myself?

 

Give these guys a try

CAMSKILL PRODUCTS Lambda Sensor- Oxygen Sensor 3 Wire EJ20 EJ20 up to 1997 : £89.00 : Subaru Impreza Turbo Parts, Tuning, Spares & Accessories : Engine - Misc -

If you want a cheaper one, do a search for a universal type.

You can fit it yourself, I let a mechanic do mine but I'm lazy.

Good Luck

 

not sure where to get them but it should be easy enough to fit youself,it's only a few wires that plug into the ecu....when mine went in my pug 306 peugeot wanted £70 odd + fitting so i went to quick fit & they put a universal 1 in for £25 & it worked fine...

 

i've been onto a company and they've said there's no direct fit listed, but recommended a bosch universal one?

http://www.lambdasensor.com/main/muniversal.htm

The LS02 sensor.

Can anyone tell me if this sensor will be okay? Or should i try get a proper subaru one?

 

Very VERY bad idea on a cold engine.
A direct replacement from Roger Clark Motorsport or other specialists will plug straight into the existing plug.
An after market from Andrew Page or similar motor factor will cost less but you will have to sort out the connection to the plug as it is not a direct plug in and you will have to see if it is 3 or 4 wire and then work out the wire colour connection sequence.
If you are not technical and don't have tech assistance nearby then the O/E is far simpler to fit.

 

I know mate. I've got remote start fitted to my clifford alarm, so the car's always running for 15 minutes or so before i get in it.

As for the wiring, i'm not afraid to cut the wiring and solider or crimp the connections. Would the wires not be the same colour?

Where abouts is the lamda sensor, is it easy for me to get to?

 

unfortunatly not.. if it did it wouldn't run that rich as the fuelling base map won't be far out.. the ecu doesn't realise the lambda has failed as it works on such a small voltage 0-1volt so there is no condition with a sensor fitted where the ecu can know it has failed, not with the simple method used for sensor failure detection anyways.. it will only ignore and use the fuel map if it throws a CEL.. for which there is only really the option of unplugging it..
It runs rich as the sensor usually fails at a lower voltage than it should be reading at a given point in the fuelling.. therefore the ecu thinks the engine is running lean and corrects the fuelling to what it believes to be correct.. but is in fact rich.. hence the rich running.

Simon

 

thanks for the indepth explanation Simon.

I took the car to pro sport about 4 weeks ago with this low mpg problem. they said the car was reporting an error with the Engine Coolant Temperature Sensor. Basically, the car was overfuelling because it constantly thought the engine was cold. So they replaced the sensor and cleared the error codes.

The mechanic who worked on it at the time said the lamda was 'lazy' when it was cold, and that it needed monitoring over time.

It's only in the last week or two that the car's started to idle funny like this.

What do you recommend i do to fix this problem Simon?

If i replaced the sensor myself, would i need to reset the ecu? If so, how?

Cheers

 

coolant temp sensor would also drink lots of fuel...

or did they fix it?

A lazy lambda would also cause it to drink fuel.

Simon

 

cheers simon, just updated the post for you.

They replaced the coolant temp sensor. Made things a little better i think, but it's still doing about 18mpg.

 

Replace the coolant sensor.
What model and year and I will get you the lambda location and if you tell me how many wires and their colour I can give you the connection info.

 

Thanks harvey, it's a 1995 import wrx.

They replaced the sensor and took £165 off me

 

i had a simualr problem on mine whic is a my99 turbo 2000 except on mine the the maf was knackard and the lamba sensor and the knock sensor i you could smell the over fueling in side the car it was that bad now they are all fixed and its soon to be mapped the fueling should be a lot better and my wallet wont be open so much down the petrol station

 

You got me there soz wasn't think straight.

with it disconnected it will run the base map.
when they fail they usually cause the AFR to go rich due to the incorrect reading being recieved from the sensor.

 

Good stuff.

Apparently the MAF's on the earlier one's are bullet proof. Plus when I had it at ProSport, I asked the guy if the MAF was ok and he said it was - but the Lambda was lazy and needed 'watching'.

4 weeks later and the car starts to idle like a tractor on cold startup. Think the mechanic had a point....

 

sounds like he was right just change the lamba they are bout 75quid form subaru delear and the go in the down pipe

 

Had my lambda replaced some months ago, found out it was knackered due to not passing MOT, got a new one and passed MOT, but i cant see any difference in mpg what so ever, get same mpg as before

 

Maybe yours wasn't overfuelling? Mine passed with this Lambda back in October?

 

Agree that the Lambda is faulty, but this is a 95my Import, so the Sensor is fitted in the RH Exhaust Header (Not The Downpipe) & the cost of one of these is about £195 from the factory. Be carefull if you go for a universal one as some of the early Subaru Lambda Sensors worked on a 5v scale and most universal ones are 1v.

 

How do I access it to replace it?

 

I’ve just got off the phone with a company called Fuel Parts about a replacement Lambda sensor. He said I need a part "LB1912". I gave him my VIN and Engine Type.



Does this look like the correct part - anybody used them before?

It’s not a genuine Subaru part, but it does come with 12 months warranty, and is an OE part – manufactured to the manufacturers specification. I said “is it a direct replacement becayse I’m going to fit it myself?” and he replied with “Yeah, we supply Ford, and that I’ve fitted stuff to a 350Z and an Astra GSi Turbo and they’ve been fine. No problems”.

They want £60.78 for the sensor. Delivered, including VAT.


Roger Clark Motorsport, quoted me £168.72+vat + delivery for a genuine Subaru part. (I assume it's genuine because of the price)

What do I do? RCM recommend fitting a genuine part (but they would cos they sell them), but it’s nearly 4 times as expensive as a direct replacement OE part? I know I should really fit a Subaru part, but at 4 times the cost?

 

I'm at work at the mo and have restricted access to the internet so can't look at http://www.onlineautomotive.co.uk/im...ent/LB1912.jpg . Does the sensor your looking at here have a wiring harness that is over 2 feet long?

 

I think it looks to be about 8 - 12 inches?

 

I got a generic 3 wire for mine, but i am going to have to change it due to the car giving a CEL and basically not liking the Lambda. So Will be needing a new one that works. Dont go for the cheap ones if you can help it.

 

Where did you get yours from? What year and model is your car? What's 'giving a CEL'?