P0385 Crankshaft position sensor B circuit malfunction

Crankshaft position sensor B circuit malfunction

P0385 in short

P0385 means the engine computer is not getting a proper signal from crankshaft position sensor B. A failed sensor or damaged wiring is the usual cause. Depending on whether a backup signal exists, the car may start hard, run rough or not start at all. Get it checked soon, because it can stall.

The crankshaft position sensor tells the engine computer how fast the engine turns and where each piston is. The computer uses it to time fuel and spark. When the signal from sensor B is missing or wrong, it stores P0385.

TroubleCodes.net and the Delaware DMV list both give the same generic title: crankshaft position sensor B circuit malfunction. The code does not say which part failed, only that the circuit did not report properly.

The sensor, its wiring and its connector are the usual suspects. TroubleCodes.net also lists wrong clearance to the reluctor ring and, on some Fords, electrical interference from a failing alternator.

Most likely causes

These are general causes for this code across vehicles. None is specific to one make or model.

  1. Crankshaft position sensor that is open, shorted or worn

    Common general cause
    Why it ranks here
    TroubleCodes.net lists a faulty sensor from age, damage or corrosion first. An owner of a 2001 Seville reports the scan showing this code with a failed crankshaft sensor B.
    What would change this
    Rises if resistance is open or shorted, or the signal is missing while cranking. Falls if the sensor tests normal.
    How to test the crankshaft position sensor

  2. Damaged wiring or connector between the sensor and the computer

    Common general cause
    Why it ranks here
    TroubleCodes.net lists rodent damage, age-related deterioration, broken connectors and damaged insulation, and says to inspect the harness back to the computer.
    What would change this
    Rises if wiring is chafed, chewed or the connector is corroded. Falls if the harness tests clean end to end.

  3. Sensor fitted wrongly or at the wrong distance from the reluctor ring

    Possible — needs testing
    Why it ranks here
    TroubleCodes.net lists poor installation or incorrect clearance. It mostly matters after the sensor has been removed or replaced.
    What would change this
    Rises if the code began after work near the sensor. Falls if the sensor is fully seated.

  4. Electrical interference, such as a failing alternator diode (some Fords)

    Possible — needs testing
    Why it ranks here
    TroubleCodes.net says alternator diode problems can disturb the signal on some Ford vehicles. It is a narrow cause, so it ranks last.
    What would change this
    Rises on a Ford with charging-system symptoms or a noisy charging output. Falls on any other make or a healthy charging system.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all stored codes and freeze-frame data with a scan tool, and note any other crankshaft or camshaft codes stored with P0385.

    Low riskTool: OBD-II scan tool

    • IfOther crank or cam codes are stored

      It meansNote them for the shop; the wiring or the computer may be involved.

      Go to step 2

    • IfOnly P0385 is stored

      It meansLook at the sensor wiring next.

      Go to step 2

  2. With the engine off, inspect the crankshaft sensor connector and visible harness for damage, corrosion, rodent chewing or loose pins, and check the sensor is fully seated.

    Low risk

  3. Have the sensor resistance checked with a multimeter for an open or short, and have the harness between the sensor and the computer tested.

    Use cautionTool: multimeter

    Warning:Keep hands, hair and tools clear of belts and fans if the engine is cranked for any part of the test.

Symptoms

  • Check engine light on
  • Engine does not start, or cranks and stalls
  • Engine dies while driving Gets more serious: stop and have it checked.
  • Hard starting, rough idle or weak acceleration

How to fix

  1. With the engine off, look over the crankshaft sensor connector and visible wiring for damage or corrosion.

Parts and cost context

  • Crankshaft position sensor:Test the sensor and wiring before replacing it. The sensor is often hard to reach, so labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Cadillac

  • 2004–2005 · Deville

    Supported by vehicle data

    GM bulletin 040604060 covers an engine that cranks without starting and has no injector pulses, with P0385 among the codes. The summary names the 2004-2005 DeVille. Whether it is still current is not verified.

  • 040604060Status unverified

    No start, no injector pulses, DTCs including P0385

    2004–2005deville · issued · NHTSA 10011044

    Lists P0385 among several codes set when the engine cranks but does not start and there are no injector pulses. The summary does not give the repair.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Pontiac

  • 2004–2005 · Bonneville

    Supported by vehicle data

    The same GM bulletin 040604060 names the 2004-2005 Bonneville. Whether it is still current is not verified.

  • 040604060 (pontiac)Status unverified

    No start, no injector pulses, DTCs including P0385

    2004–2005bonneville · issued · NHTSA 10011044

    Lists P0385 among several codes set when the engine cranks but does not start and there are no injector pulses. The summary does not give the repair.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0335Crankshaft position sensor A circuit fault

    Same system Possible — needs testing

    P0335 is the circuit malfunction code for crankshaft sensor A. Both point at the crankshaft signal path, so check shared wiring and the computer if both are stored.

All Ignition and engine position sensors codes

P0385 questions

Can P0385 make the engine die while I drive?

Yes. An owner reports the engine dying with loss of steering assist, and TroubleCodes.net lists stalling. Treat a stall in traffic as a stop-and-tow situation.

Sources and review

  1. TroubleCodes.net DTC pages (P0342, P0385, P0394, P0400, P0431, P0447; P0413, P0414, P0416, P0417 read but not used) — TroubleCodes.net
  2. NHTSA complaint ODI 10226853: 2001 Cadillac Seville — NHTSA Office of Defects Investigation (consumer complaint)
  3. On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles
  4. GM 040604060: Engine cranks but does not start, no injector pulses, DTCs including P0385 (2004-2005 DeVille, Bonneville, 2004 Seville) — GM / NHTSA ,
Last reviewed
Written by
Saurabh K.
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