Evening all

 

My car is throwing up the P0546 code and intermittently goes into limp mode when I put my foot down and I loose power. The code indicate the upstream Lambda sensor is the problem so I've had it replaced with an OEM part. Still the issue persists and the code remains.

 

Does anyone have any suggestions what could be at fault?

 

Thanks

EGT sensor and Lambda sensor are different parts, you need to replace the EGT sensor.

14 hours ago, sepulchrave said:

EGT sensor and Lambda sensor are different parts, you need to replace the EGT sensor.

Thanks for getting back. The error code points directly to the lambda sensor but its fine it's rules out it being the problem but if I'm honest the issue is seemly starting to clear.

 

I honestly think it needs a forced regeneration as it has just been doing short distance for the last year or so. 

 

I'm not sure that the rad fan is spinning either so I will be replacing the temp sensor too to see if that clears up anything 

34 minutes ago, Fanty111 said:

The error code points directly to the lambda sensor

Not according to your screenshot, nor google.

What's awkward for you is that there may be 3 exhaust gas temperature sensors in your exhaust system, so you'd do well to get a less generic fault code to narrow down which is being detected as faulty. VCDS Lite will do for scanning your car.

 

Rad fan may well be the fan itself rather than any sensor or thermoswitch. Can guide you to testing it out, please say if the car has working A/C or not.

1 hour ago, Breezy_Pete said:

Not according to your screenshot, nor google.

What's awkward for you is that there may be 3 exhaust gas temperature sensors in your exhaust system, so you'd do well to get a less generic fault code to narrow down which is being detected as faulty. VCDS Lite will do for scanning your car.

 

Rad fan may well be the fan itself rather than any sensor or thermoswitch. Can guide you to testing it out, please say if the car has working A/C or not.

Hi pal. When I took it in the mechanic used his tool and it flagged as Bank 1 sensor 1 which suggests upstream. The car does NOT have working AC.

 

The plan is the keep ragging it around until Tuesday. How likely is this a DPF issue?

Ask the mechanic what the exact fault code was, unless it was the same as in your picture?

Bank 1 sensor 1 could refer to a lambda sensor or a temperature sensor, so no use without the code number.

 

For fan testing I would recommend disconnecting the radiator thermoswitch (just above bottom hose connection) and bridging contacts of the loom plug. 

Will provide a marked-up picture shortly.

 

No idea about DPFs, sorry.

11 minutes ago, Breezy_Pete said:

Ask the mechanic what the exact fault code was, unless it was the same as in your picture?

Bank 1 sensor 1 could refer to a lambda sensor or a temperature sensor, so no use without the code number.

 

For fan testing I would recommend disconnecting the radiator thermoswitch (just above bottom hose connection) and bridging contacts of the loom plug. 

Will provide a marked-up picture shortly.

 

No idea about DPFs, sorry.

The fault code P0546. When driving, it feels like it need to go bang and clear out the back it's hard to explain. Driving it this morning it was fine but I'm driving it in low gear and high revs to get the temperature high and to try and force a regen 

27 minutes ago, Breezy_Pete said:

What is this?

See paragraph about fan testing in an earlier post of mine up there ^.

32 minutes ago, Breezy_Pete said:

See paragraph about fan testing in an earlier post of mine up there ^.

Mate that's brilliant I will keep you updated on how it goes

1 hour ago, Fanty111 said:

How likely is this a DPF issue?

As the first reply poster put it appears to be, according to your photo of the scan tool, a possible problem with, or to, or at, the "Exhaust Gas Temperature Sensor" which if left unresolved may lead to a problem with the DPF if the car's computer doesn't get to do its jobs properly.

 

You could perhaps try unplugging the EGT sensor and see what different readings or codes you get on your scan tool.

 

You could perhaps just resolve by doing as you're doing and taking the car on blow-out runs and unless it seem too frightening do the blow-out runs using a couple of tankfulls of V-Power.  Or if you like getting dirty dry cleaning the sensor.  Or if you like spending on new parts replace the sensor - but check it with a multimeter first and check the wiring and connections, you already know someone here to help you with that.

 

With your photo if you held the phone at landscape instead of portrait you'd have a better image of the scan tool screen.

 

Edited 27 April, 20233 yr by nta16
spelling

8 hours ago, Fanty111 said:

 I honestly think it needs a forced regeneration as it has just been doing short distance for the last year or so. 

 Do you have a specific reason for suggesting a forced regen. I would suggest trying to find someone local from the VCDS listing on here to do a forced regen for you - this is quite easy with VCDS, and being VAG specific would give some confidence on the code seen - but would also suggest trying to find out what temp the car is running at as the "blue light" is an unreliable method of identifying coolant temp as it extinguishes at 45 deg.C and I found out through Torque and a bluetooth dongle that my Greenline had a defective thermostat and was running cool. Regen requires a high coolant temp to initiate.

 Have you identified it doing a regen, the exhaust note on mine changes when initiated which I liken to a moose bellow.

Edited 27 April, 20233 yr by KeithCheetham

49 minutes ago, KeithCheetham said:

 Do you have a specific reason for suggesting a forced regen. I would suggest trying to find someone local from the VCDS listing on here to do a forced regen for you - this is quite easy with VCDS, and being VAG specific would give some confidence on the code seen - but would also suggest trying to find out what temp the car is running at as the "blue light" is an unreliable method of identifying coolant temp as it extinguishes at 45 deg.C and I found out through Torque and a bluetooth dongle that my Greenline had a defective thermostat and was running cool. Regen requires a high coolant temp to initiate.

 Have you identified it doing a regen, the exhaust note on mine changes when initiated which I liken to a moose bellow.

It was running at temp of 80-90 degrees. Is that normal? Mines also a greenline

Update: The plot thickens...

 

Taken out for a 60 mile blast and on the return leg the issues become more persistent. I also noticed the fans started blowing cooler air and when I get home I checked the engine bay and the rad fan didn't come on like it should.

 

Any ideas?

On 26/04/2023 at 19:57, sepulchrave said:

EGT sensor and Lambda sensor are different parts, you need to replace the EGT sensor.

I have an ongoing theory.

 

I think the coolant temp sensor is bad. The engine isn't getting super hot and the rad fan isn't going on. Which therefore would mean that it isn't getting hot enough to do a DPF regen and therefore building emissions 

It's not regenerating, it's simply not getting hot enough and that fault code is probably not helping.

 

Edit: SNAP!

Edited 27 April, 20233 yr by sepulchrave

2 hours ago, sepulchrave said:

It's not regenerating, it's simply not getting hot enough and that fault code is probably not helping.

 

Edit: SNAP!

What is your advice given the extra details I have provided?

13 hours ago, Fanty111 said:

It was running at temp of 80-90 degrees. Is that normal? Mines also a greenline

Just to clarify and for my info, was this based on an instrument cluster reading as my Greenline only has the blue light and no temp gauge. 80 to 90 degrees is normal as the thermostat will have a set point to maintain 90 deg.C as a max/normal.

 Sounds as like @sepulchrave suggested you need to get a forced regen carried out using VCDS or similar - this will overide the requirement for ECU input to initiate a regen. After this a code clear would give the ECU a baseline to possibly report factual codes.

Edited 28 April, 20233 yr by KeithCheetham

On 28/04/2023 at 09:24, KeithCheetham said:

Just to clarify and for my info, was this based on an instrument cluster reading as my Greenline only has the blue light and no temp gauge. 80 to 90 degrees is normal as the thermostat will have a set point to maintain 90 deg.C as a max/normal.

 Sounds as like @sepulchrave suggested you need to get a forced regen carried out using VCDS or similar - this will overide the requirement for ECU input to initiate a regen. After this a code clear would give the ECU a baseline to possibly report factual codes.

So after looking into this further, thermostat came off and tested all fine. Coolant temp sensors all fine. Rad fan is working fine. There was an issue with the water flow that that's why it didn't get the op temp properly. When the drain plug was released no anti freeze came out and when the coolant was dropped via the bottom radiator hose it was stone cold after running for 30 minute.

 

Right now it doesn't feel like the DPF is the issue, more that the turbo isn't kicking in due to a poor fuel/air mix. The sensors around the turbo, DPF and Cat are getting tested tomorrow. When we disconnected the Lambda sensor connector the car started to read a P0135 fault which I believe is the o2 sensor.