P24C6 Particulate Matter Sensor Temperature Circuit GLC250D 2018 WDC253909

mineauto · Jan 30, 2024

P24C6 Particulate Matter Sensor Temperature Circuit GLC250D 2018 WDC253909

Has anyone had any experience with this?

The fault light/code just came on for it today.

I think it's a sensor screwed into the side of the exhaust downstream of the cat.

Could be dirty, faulty or the wiring loom is damaged or loose.

Looks easy enough to replace but just wondered if anyone has experienced troubleshooting one of these before. I'd rather not spend £200 on a sensor if soot buildup or damaged wiring are the culprits.

A bit of car history: typically my car does plenty of 50-mile-long journeys commuting to work. However, for the last 5 months, I've been off long-term sick recovering from an arm injury so for 6 weeks the car went nowhere and then I've only done sub 1 mile journeys for the last few months. Could this be a cause of excessive soot buildup with few chances for burn-off?

Or do I just need to stick some cat cleaner in the tank and drive it a bit more? (back to work this week)

Cheers, mineauto

mineauto · Sep 16, 2024

Update.

I drove around for months with the fault. Didn't go away. Car all normal throughout.

Today I decided to part with the cash for the part, £380 in vat from Merc official spares (found it a bit cheaper elsewhere but you get part and labour warranty if you buy from Merc direct).
(part ref A 000 905 06 08 Soot Particulate Sensor)

I swapped the unit; it was quite a simple job. The fault code cleared and has stayed clear.

Thinking back to when this failed there had been some flooding locally. The part is vulnerable if you wade through anything that reaches the bottom of the door sills. It is tucked away behind plastic shields but water will get to it if you go through a flood. If they do die when submerged, then it's an expensive bit of wading.

If you do it yourself you'll need a 24mm spanner and heat or brute force to remove it from the exhaust. There are 2 sensors close to each other, the NOX sensor has a smaller 22mm nut and is towards the rear of the vehicle. The particulate sensor is closest to the front of the car. You'll need to remove 3 or 4 nuts to pull back the plastic under the car shield to get to it, no need to remove the whole shield.