OBD Particulate Matter Sensor Circuit High
What it means
P24B1 stands for Particulate Matter Sensor Circuit High. P24B1 is a P code, so the fault sits in the engine, transmission and emissions systems. For P24B1, the second digit places it in auxiliary emission controls. For P24B1, work through the cause list below, cheapest checks first.
Where it lives
For P24B1, the sensor sits on the circuit this code reports. The description of P24B1 reports a fault at the sensor.
What to check first
For P24B1, pull the connector and inspect the terminals for spread, corrosion or backed-out pins before testing anything else.
Check these first
- P24B1: Carbon buildup or blockage in the EGR, EVAP, or air injection system
- P24B1: Failed solenoid, valve, or pump in the auxiliary emissions circuit
- P24B1: Wiring, connector, or fuse fault for the emission component
- P24B1: Small leaks in vacuum or EVAP lines
- P24B1: Failing catalytic converter or oxygen sensor reporting incorrectly
What to do next
P24B1 belongs to the auxiliary emission controls system. These are the general steps for P24B1, and the exact cause on your vehicle can differ.
- P24B1: Read related codes and freeze frame with an OBD-II scanner
- P24B1: Inspect hoses, valves, and solenoids for leaks, cracks, or carbon buildup
- P24B1: Smoke test the EVAP or intake system if a leak is suspected
- P24B1: Command components on/off with a scan tool and watch them respond
- P24B1: Clean or replace the blocked or failed component
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Updated
Generic SAE J2012 definition. Last updated 2026-08-30.