P24C6: Particulate Matter Sensor Temperature Circuit

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.

P24C6 is a emissions-related diagnostic trouble code classified as low severity. When your vehicle's ECU detects this condition, it stores P24C6 and illuminates the check engine light.

If your vehicle has triggered P24C6, you may notice one or more of these symptoms:

• 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

Here are the most common causes of 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.

Follow these steps to pinpoint the root cause of P24C6:

1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
6. Run any learning procedure the engine computer asks for, clear the code and drive normally so the filter monitor can run again.

Repair costs for P24C6 vary depending on the root cause and your vehicle. Here are typical estimates:

P24C6 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

These codes are often seen alongside P24C6 or indicate related issues: