Lambda sensors

[Dan_Moore]

Mot garage have told me I need 2 lambda sensors to pass emissions, apparently its running rich, at a cost of £450 inc labour.

Now I'm a little dubious about this, not the price so much just the need for the 2 sensors so would welcome any feedback or if there's a way I can check using obdeleven?

[Deano]

Doesn’t sound right. I’ve not looked into the O2 sensors on the Golf tbh, but on every other car I’ve owned the pre cat O2 sensor adjusts your fuel trims and the second sensor post cat is just there to ensure the cat is working. The second sensor usually doesn’t have any effect on the cars fuelling. 

[dv52]

Dan: hi.

 

With no offense to @Deano (his advice is generally correct) -  .it really does depend on the exact nature of the error code(s)

 

I might be completely off-track (quite possibly I am - if so, my apology) - but I note that your previous replies on this forum were made with reference to the Golf R.

 

So, I suspect that this vehicle might have a 2.0l engine - possibly CJX-series engine, or CYFB (2.0 l, 4 V, turbocharger, chain drive, generation III) Volkswagen R GmbH). Again, if so, -this engine does have 2 x lambda probes, called CX7 and CX10

 

On my picture:

• 1 = Lambda probe after catalytic converter - GX7-
• 2  = Lambda probe before catalytic converter - GX10-

 

Do you access to a diagnostic device? If so - the Engine Control Module (ECU) will generally be able to tell you what's happening to each of the 2 x sensors.

 

Don

PS: £450 sounds a tad steep - but then our Aussie dollar (colloquially known as  the "Pacific Peso")  is a real mess, so maybe this is the reason for my surprise? 

 

[Dan_Moore]

7 hours ago, Deano said:

Doesn’t sound right. I’ve not looked into the O2 sensors on the Golf tbh, but on every other car I’ve owned the pre cat O2 sensor adjusts your fuel trims and the second sensor post cat is just there to ensure the cat is working. The second sensor usually doesn’t have any effect on the cars fuelling. 

Thanks that's what I thought as well.

[Dan_Moore]

5 hours ago, dv52 said:

Dan: hi.

 

With no offense to @Deano (his advice is generally correct) -  .it really does depend on the exact nature of the error code(s)

 

I might be completely off-track (quite possibly I am - if so, my apology) - but I note that your previous replies on this forum were made with reference to the Golf R.

 

So, I suspect that this vehicle might have a 2.0l engine - possibly CJX-series engine, or CYFB (2.0 l, 4 V, turbocharger, chain drive, generation III) Volkswagen R GmbH). Again, if so, -this engine does have 2 x lambda probes, called CX7 and CX10

 

On my picture:

• 1 = Lambda probe after catalytic converter - GX7-
• 2  = Lambda probe before catalytic converter - GX10-

 

Do you access to a diagnostic device? If so - the Engine Control Module (ECU) will generally be able to tell you what's happening to each of the 2 x sensors.

 

Don

PS: £450 sounds a tad steep - but then our Aussie dollar (colloquially known as  the "Pacific Peso")  is a real mess, so maybe this is the reason for my surprise? 

 

Hi Don thanks for your reply. It's a cjxc 2014. No lights on dash, no codes on obdeleven. ( this led me to believe they might not be correct with their diagnosis)

Is there a way to test the sensors using obdeleven?

[Dan_Moore]

Just checked my mot online and see I have an exhaust leak, after having a quick look underneath its from the rear joiner from the res delete, an easy fix. 

Question is surely that's affecting the readings they take for emissions? Plus they never mentioned the headlight to me either. 🙄

[Deano]

9 minutes ago, Dan_Moore said:

Just checked my mot online and see I have an exhaust leak, after having a quick look underneath its from the rear joiner from the res delete, an easy fix. 

Question is surely that's affecting the readings they take for emissions? Plus they never mentioned the headlight to me either. 🙄

Yes, an exhaust leak (even a small one) can affect the lambda reading. Had this myself on a Honda a few years ago. Sorted the leak and all was good.

 

I suspect you have the same issue. Additionally, if the car is running rich it will usually fail on high CO, whereas you appeared to have failed on a high lambda reading pointing to an exhaust leak, which ironically the MOT tester has also identified.

[Dan_Moore]

1 minute ago, Deano said:

Yes, an exhaust leak can affect the lambda reading. Had this myself on a Honda a few years ago. Sorted the leak and all was good.

 

I suspect you have the same issue.

Yeah makes sense mate cheers.

The more I investigate this the more it points to the garage just guessing, just trying it on or both.

I'll sort exhaust and headlight and try again somewhere else. 

First and last time I'll use this company. 

[mustard]

Just had a quick check on Euro Car Parts, the two sensors are around £300 for the pair, and judging by my local dealer, they probably are charging an hour's labour for the £450

[Deano]

On 16/07/2024 at 08:53, Dan_Moore said:

Yeah makes sense mate cheers.

The more I investigate this the more it points to the garage just guessing, just trying it on or both.

I'll sort exhaust and headlight and try again somewhere else. 

First and last time I'll use this company. 

Let us know how you get on.

[Dan_Moore]

Quick update. Over the weekend I adjusted the headlight and tightened the exhaust clamp. It sailed through the mot this morning with no advisories.

Just shows how bad some mot garages are and that loads of people must get ripped off buying parts that aren't needed.

[Deano]

On 23/07/2024 at 09:41, Dan_Moore said:

Quick update. Over the weekend I adjusted the headlight and tightened the exhaust clamp. It sailed through the mot this morning with no advisories.

Just shows how bad some mot garages are and that loads of people must get ripped off buying parts that aren't needed.

I don’t know if garages are trying it on or are just generally incompetent to tbh.

 

Glad it’s all sorted.