What does it mean?
This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to OBD-II equipped vehicles. Although generic, specific repair steps may vary by make/model.
The crankshaft position sensor (CKP) measures the location of the crankshaft and transmits this information to the PCM (Powertrain Control Module). Depending on the vehicle, the PCM uses this crankshaft position information to properly time the spark, or on some systems, it is only for misfire detection and does not control spark timing.
The CKP sensor is fixed and works in harmony with a reluctor ring (or toothed ring) that is attached to the crankshaft. When this reluctor ring passes in front of the CKP sensor, the magnetic field created by the CKP sensor is interrupted, which creates a square wave voltage signal that the PCM interprets as the crankshaft position. If the PCM detects that there are no crankshaft pulses or if it sees a problem with the pulses on the output circuit, P0385 will be set.
Related Crankshaft Position Sensor B fault codes:
P0386 Crankshaft Position Sensor B Circuit Range/Performance
P0387 Crankshaft Position Sensor B Circuit Low Input
P0388 Crankshaft Position Sensor B Circuit High Input
P0389 Crankshaft Position Sensor B Circuit Intermittent
Symptoms
NOTE: If the crank sensor is used only for misfire detection and NOT for spark timing (this varies by vehicle), the vehicle should start and run with an illuminated MIL (Malfunction Indicator Lamp). Additionally, some vehicles require multiple key cycles to illuminate the MIL. If this is the case, there may be no MIL illumination until the issue becomes frequent enough over time. If the crank sensor is used for both misfire detection and spark timing, the vehicle may or may not start. Symptoms may include:
The vehicle may not start (see above)
The vehicle may run rough or misfire
MIL illumination
Causes
A P0385 “Check Engine Light” code could be caused by:
Damaged CKP sensor connector
Damaged reluctor ring (missing teeth or not rotating due to a sheared keyway)
Open sensor output
Sensor output shorted to ground
Sensor output shorted to voltage
Faulty crankshaft sensor
Failed PCM
Possible Solutions
Using a scan tool, check whether, when the engine is cranking or running, there is an RPM signal.
If there is no RPM reading, visually inspect the B crank sensor connector for any damage and repair if necessary. If there is no visible damage and you have access to a scope, you can check the CKP 5-volt square wave pattern. If you don’t, get a resistance reading for your crank sensor from a repair manual. (There are so many different types of crank sensors that there is no way to indicate here which resistance value is correct). Then check the CKP sensor resistance by disconnecting the B sensor and measuring the resistance. (It is best to check resistance readings from the PCM connector. This rules out any wiring issues from the start. But this requires some mechanical skill and should not be performed if you are not familiar with automotive electrical systems). Does the sensor meet resistance specifications?
If not, replace the CKP sensor. If it does, recheck the resistance reading from the PCM connector. Is the reading still correct?
If not, repair the open or shorted B crank sensor wiring and check again. If the reading is correct, the problem is intermittent or the PCM may be at fault. Try reconnecting and checking the RPM signal again. If there is now an RPM signal, test the wiring harness to try to induce the fault.
This code is basically identical to P0335. This P0385 code refers to the “B” crankshaft position sensor, while P0335 refers to the “A” crankshaft position sensor. If you have code P0385, your vehicle is equipped with two crank position sensors (CPS). Other crank sensor codes include P0016, P0017, P0018, P0019, P0335, P0336, P0337, P0338, P0339, P0385, P0386, P0387, P0388, and P0389.