P24C6: Particulate Matter Sensor Temperature Circuit
Quick Answer
Safe to drive (short-term)
P24C6 means the engine computer has found a fault in the temperature circuit of the particulate matter sensor, also called the soot sensor. This sensor sits in the exhaust after the diesel particulate filter and checks that the filter is still trapping soot. Before each measurement it heats itself to burn off collected soot, and it needs its own temperature reading to do that, so with this fault the sensor cannot work and the engine cannot confirm the filter is doing its job. The usual causes are a failed sensor or a wiring or connector fault; the particulate filter itself is usually fine.
- Severity
- Low · Emissions
- Estimated repair cost
- From €30 to €620+, varies by vehicle
€30 or €620, depending on your car.
- Adapt or relearn a new sensor with diagnostic software (where required)€30–€80
- Replace particulate matter (soot) sensor€190–€620
A scan shows whether P24C6 is really stored on your car, which codes sit next to it and how urgent each one is.
A scan needs a Bluetooth OBD2 adapter (Bluetooth LE on iPhone), about €25-60; the built-in demo runs without one. See which adapter to buy
What does P24C6 mean?
P24C6 is a emissions-related diagnostic trouble code classified as low severity.
What are the symptoms of P24C6?
- Check engine light on
- No change in how the car drives on most vehicles
- Other particulate matter sensor codes (heater or signal circuit) stored alongside on some cars
- Particulate filter monitoring shown as not complete or not ready in a readiness check
- Vehicle inspection can be rejected while the check engine light is on; rules vary by country
What causes P24C6?
Failed particulate matter sensor (internal heater or temperature element fault)
: high
Water, corrosion or loose pins in the sensor or control unit connector
: medium
Chafed or heat-damaged wiring along the exhaust
: medium
Sensor damaged by water or by a knock from underneath
: low
Blown fuse or supply fault to the sensor's control unit
: low
Engine computer or software fault (rare)
: low
Is it safe to drive with P24C6?
Generally yes, for short-term driving. Usually safe to drive: the engine normally runs as before, and this sensor checks the particulate filter rather than controlling the engine. The engine computer cannot confirm the filter is working while the fault is present, and the check engine light stays on, so a vehicle inspection can be rejected; rules vary by country. Book the repair rather than leaving it for months.
How do you diagnose P24C6?
- Read all stored codes and the freeze frame with an OBD2 reader. Note any other particulate matter sensor codes and any particulate filter codes such as P2002, P2463 or P244B. A generic OBD2 reader shows the codes, the freeze frame and the readiness status, but not the sensor's internal readings; those need manufacturer-level software.
- Confirm that the part at fault is the particulate matter sensor after the filter, not the DPF pressure sensor or a NOx sensor. They can sit close together under the car and are different parts.
- Check the fuse for the sensor supply, then inspect the sensor lead and its control unit connector for water, corrosion, pushed-back pins and heat or impact damage along the exhaust.
- With manufacturer-level software, read the sensor's status and temperature values, and run its self-test if the software offers one. A temperature value that is missing or impossible with good wiring points to the sensor.
- Replace the sensor if the wiring and supply are good. On many cars the probe, its lead and its control electronics come as one part. An old sensor can be seized in the exhaust, so heat or penetrating oil may be needed.
- Run any learning procedure the engine computer asks for, clear the code and drive normally so the filter monitor can run again.
How much does P24C6 cost to fix?
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Replace particulate matter (soot) sensor | €150–€500 | €40–€120 | €190–€620 | Moderate |
| Clean and repair sensor connector | €10–€60 | €60–€180 | €70–€240 | Moderate |
| Repair sensor wiring harness section | €20–€120 | €120–€350 | €140–€470 | Professional |
| Adapt or relearn a new sensor with diagnostic software (where required) | €0–€0 | €30–€80 | €30–€80 | Professional |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
P24C6 on specific vehicles
P24C6 on Mercedes-Benz
Mercedes-Benz C-Class diesel · Mercedes-Benz GLC 220d / 250d
Related diagnostic codes
Common questions about P24C6
- What does P24C6 mean?
- P24C6 means there is a fault in the temperature circuit of the particulate matter sensor, the soot sensor fitted after the diesel particulate filter. The sensor heats itself to clean off soot before each measurement and needs its own temperature reading to do that, so with this fault it cannot check whether the filter is still working.
- Is P24C6 serious?
- On most cars it is not urgent: the engine runs normally and the particulate filter keeps regenerating. The problem is that the filter can no longer be monitored, and the check engine light stays on, so a vehicle inspection can be rejected; rules vary by country. Have it fixed within weeks rather than months.
- What does a particulate matter sensor do?
- It measures how much soot is still coming out of the exhaust after the particulate filter. Soot builds up on the sensor's electrodes and changes their electrical resistance, and the engine computer uses the result to confirm the filter is trapping soot. If the filter cracks or is removed, this sensor is what notices.
- Is the particulate matter sensor the same as the DPF pressure sensor?
- No. The DPF pressure sensor measures exhaust pressure across the filter to judge how full of soot it is, and its faults set codes such as P2452 to P2455. The particulate matter sensor sits after the filter and measures the soot that gets through. They are separate parts at different prices, so check which one the code names before buying.
- How much does it cost to fix P24C6?
- A new particulate matter sensor typically costs 190 to 620 euros fitted, depending on the car and whether an original part is used. A connector repair runs 70 to 240 euros and a damaged wiring section 140 to 470 euros. Add 30 to 80 euros if the new sensor needs a learning procedure with diagnostic software.
Read our detailed guides
Sources
- xenons4u.co.uk xenons4u.co.uk/a0009050608-soot-particulate-sensor.html
- bosch-mobility.com bosch-mobility.com/en/solutions/exhaust-gas-treatment/particulate-matter-sensor/
- carparts-onlineshop.com carparts-onlineshop.com/particle-sensor-mercedes-oem-a0009050608-bosch-028100709
- forums.mbclub.co.uk forums.mbclub.co.uk/threads/p24c6-particulate-matter-sensor-temperature-circuit-