P24B0: Particulate Matter Sensor Circuit Low
What to do
Ask for the wiring and connector under the car to be checked before the sensor is replaced. This sensor sits in the exhaust stream where salt and water reach it, its harness runs under the floor, and a corroded connector or chafed wire produces this code with a perfectly good sensor.
The part is expensive, so the order of investigation genuinely matters to the bill.
Mention if the fault comes and goes with the weather. A code that appears in winter and clears in summer points firmly at water in a connector, which is useful and cheap to fix.
The car will drive normally, but the emissions monitor is out of action, so allow time before an MOT.
What this code means
The particulate matter sensor signal is below the lowest voltage the circuit should ever produce.
A signal pinned low almost always means the wire has found a path to earth, and that is where diagnosis should start. A short to ground, a chafed harness resting against the underbody, or water bridging a corroded connector all produce it.
Location is what makes this common. The sensor lives under the vehicle in the exhaust stream, its harness runs along the floor, and road salt, standing water and stone damage all reach it in a way they never reach an engine bay connector.
Distinguish the wiring from the sensor with one measurement. Unplug the sensor: if the signal stays low with the sensor disconnected, the fault is in the harness or the module, not the sensor. That single check saves the cost of a part that is not faulty, and this sensor is not cheap.
Check the connector for water before anything else. A connector that has filled and corroded reads low, dries out in summer, and comes back every winter — which is exactly the intermittent history these often have.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Water ingress into connector · easy
- Corroded or loose connector · easy
Less common
- Faulty particulate matter sensor · moderate
- Chafed wiring against the vehicle body · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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