Fault codeP0385

SEVERE

Crankshaft Position Sensor B Circuit Malfunction

What this code means

Crankshaft Position Sensor B Circuit Malfunction.

P0385 is a generic code: it means the same thing on every make. P0385 belongs to family P03xx — Ignition and misfire. Its page explains how to read a code and groups all its codes by part.

Type of fault

The control unit has detected an electrical anomaly on this circuit without saying exactly which. Diagnosis starts with a visual check of the wiring and connector, then measuring the component — resistance, supply, ground — with a multimeter.

Crankshaft position sensor (engine speed)

The crankshaft sensor faces a toothed wheel on the crankshaft or flywheel and counts its teeth as they pass. From that signal the control unit knows the engine speed and the exact position of the pistons: it is the reference for all ignition and injection timing.

What you notice

Without this signal the engine cannot run. A failing sensor typically causes a sudden stall, often when hot, or an engine that cranks but will not start; the rev counter may drop to zero while driving.

How to check it

Look at the connector and the wiring near the gearbox or the crankshaft pulley, where it is exposed to heat and dirt. Clean metal debris off the sensor tip, and check the toothed wheel for missing or damaged teeth. If the engine still runs, Klaro's rev reading dropping out at the moment of a stutter is a strong clue.

Watch it live in Klaro

With an OBD2 adapter plugged in, these live readings show the part at work, when your car reports them:

Engine RPM
Timing advance

What to do

Have it checked promptly. A misfire sends unburnt fuel into the exhaust and destroys the catalytic converter within a few dozen kilometres. If the light is flashing, stop driving.

Clearing a code switches the light off but repairs nothing: if the fault remains, the code comes back. Clearing a fault code yourself →

How to read this code

PPowertrain
0standardised code
3Ignition and misfire
85P0385