EML on. Which exhaust gas temperature sensor ? Please Help

[DMitch16]

You'll know when you remove the old one as the sensor body should be the same length as the old one and you'll be able to plug it in to the ECU feed. My MIL light went off straight away on changing the lower sensor but now I'm having boost problems from the turbo which may be leaking oil...all good fun! BTW Where did you order the top sensor from and how much if you don't mind me asking?

Good luck and keep us posted!

[Radders567]

He bought it from VW @ approx £125 inc vat

[Radders567]

Just a quick update. I changed the top sensor as discussed 2 days. Reset the fault code and took it for a drive the re scanned it with VCDS. No fault codes were present. My dad has been driving it for 2 days and now the dreaded light is back on !!!!. I am going to re scan it to find out the fault code this time and I will post again soon.

[DMitch16]

Mine did exactly the same except this time the Boost Pressure Solenoid is at fault (the N75) fortunately a somewhat cheaper and easier fix. BTW did the new sensor you put in look exactly the same as the one you took out of the top? Would be interested to know thanks.

[davidjmac]

Hi,

I have exactly the same problem with exactly the same car. About 3 weeks ago it had a forced regen from my local dealer and they reported the filter clean. A couple of days ago the DPF light came on followed within hours by the EML. Taking the vehicle back to the dealer they are reporting the DPF is above 90% and it cannot be regenerated. I said i thought they were able to be regen'd up to 95% and why has it blocked so quickly and they claim it has a failed temperature sensor which meant the regens have been unable to be carried out and as the sensor is in the DPF the filter needs replacing anyhow. My questions are;

How did it go from good to +90% in hours without warning?
Is the sensor replaceable?
Is the +£2K they want to fix it reasonable?

Regards, David

[DMitch16]

Hi David,

The sensor is replaceable and charged by VW as per my earlier replies in this post. DIY costs vary depending on which temp sensor has failed, again read my earlier replies.

Get the sensor replaced first. The purpose of the DPF light (MIL dash warning) is to report when the DPF requires a regeneration (having not been able to perform either passive or active regenerations itself) at which point you should proceed with a forced regen by driving for at least 20 minutes at 2000rpm minimum this is around 60mph in 4th gear - for DSG gearboxes either put the gear lever in the sequential mode and work up to 4th or use sport mode which will give you the higher revs versus speed. Ensure you can drive continuously at these levels for the duration i.e. make sure you keep the revs up and have enough fuel in the tank. The fact that the DPF light came on is a normal process to warn you that the regen has not happened and the soot levels elevated but this should not mean that the DPFs life has ended.

I wouldn't be surprised at the dealer figure of £2K though for sorting this but you are lucky my friend as there is a firm called Turner Automotive (aka Turner Diagnostics) in St Albans who deal with the cleaning of blocked DPF units at around £265. Might be worth you looking into this option perhaps if you can't force a regen or VW want too many arms and legs!!?

[davidjmac]

Turner Automotive (aka Turner Diagnostics) in St Albans who deal with the cleaning of blocked DPF units at around £265. Might be worth you looking into this option perhaps if you can't force a regen or VW want too many arms and legs!!?

Thanks Mitch, Turner were helpful. They said that we ought to check the VW garage did the regen, ask for proof - of which we are still waiting. The VW garage said they did do the regen and the reason it went from nearly 0 to 215% in 8 weeks is due to a failed turbo. Thoughts?

[DMitch16]

Soot build up is rapid in turbo diesels especially when the regenerations don't happen due to other issues. A failed turbo shouldn't directly cause the soot build up but whatever prevents the regenerations will e.g. faulty sensors. The light (DPF - exhaust symbol) should come on at roughly 55% of DPF saturation. Regens usually happen at around 40 to 45% saturation and you should never get the light on if all is well but each brand of car is slightly different of course. Once roughly 75% is reached it is more unlikely that a successful regeneration would take place (unlikely but not impossible) and dealer / auto shop intervention is advisable. At 95% saturation and above most dealers write off the DPF and would replace it. In your situation it very much depends how long the car was driven after the DPF light illuminated (if it did) as it does not take long for the soot to build up in the DPF.

The Turner guys deal with this type of issue regularly and have much more experience / expertise than I do but new replacement DPF units are around £650 upwards.