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P0337 – Crankshaft Position Sensor A Circuit Low Input (OBD2)

P0337 means "Crankshaft Position Sensor A Circuit Low Input". The voltage the control unit measures in the crankshaft position sensor circuit is below the permitted minimum. For a sensor this usually means the signal wire is shorted to ground or the reference voltage is missing; for an actuator, that its control wire is shorted to ground.

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P0337 quick summary

Fault codeP0337
MeaningCrankshaft Position Sensor A Circuit Low Input
SystemPowertrain (Engine & Transmission)
VehiclesGeneric OBD2
SeverityHigh
Can I drive?Not recommended. A failing crankshaft sensor can make the engine stall without warning – including in traffic – and it may not restart.
Repair cost€30 – €400

How the crankshaft position sensor works

The crankshaft position sensor tells the engine control unit how fast the engine turns and exactly where the pistons are – without it, most engines cannot start.

The sensor reads a toothed reluctor ring on the crankshaft or flywheel. A gap of one or two missing teeth marks a reference position. Older sensors are inductive (they generate an AC voltage), newer ones are Hall sensors with a 5 V or 12 V supply and a square-wave signal.

The engine control unit uses the signal for ignition and injection timing, engine speed, misfire detection and, together with the camshaft sensor, to identify which cylinder is on its compression stroke. Some systems use a second crankshaft signal (sensor B) or a high-resolution timing signal (P0370–P0379).

A failing crankshaft sensor often causes the engine to cut out when warm and restart after cooling down, or prevents starting altogether. Damaged reluctor rings, metal debris on the sensor tip and wiring damage are common causes besides a failed sensor.

On VAG vehicles (VW, Audi, Škoda, Seat, Cupra), VCDS and older VAG testers can show this code as the five-digit VAG code 16721 (P0337). Both numbers mean the same fault.

Symptoms of P0337

  • Engine cranks but does not start
  • Engine cuts out, often when warm, and restarts after cooling down
  • No rev counter movement while cranking
  • Misfires or jerking
  • Check Engine light on

Most common causes of P0337 (most likely first)

Mechanic's Pro Tip

If the engine cuts out only when hot, check the crankshaft sensor first – and test it while it is hot. A heat gun on the sensor or a test drive with live data often reproduces the fault that disappears once the engine cools down.

  1. 1.Signal or control wire shorted to ground

    Most likely

    Look for chafed insulation where the harness touches the engine, exhaust brackets or body edges.

  2. 2.Missing 5 V reference or supply voltage

    An open reference wire or a shorted sensor elsewhere on the same reference circuit can pull it down.

  3. 3.Internal short in the crankshaft position sensor

  4. 4.Failed crankshaft position sensor

    Heat makes internal faults worse – classic warm-engine cut-outs.

  5. 5.Metal debris on the sensor tip

    Magnetic sensors attract particles from wear, which distort the signal.

  6. 6.Damaged reluctor ring or wrong air gap

    Bent, cracked or loose tone rings and an incorrectly seated sensor.

  7. 7.Wiring or connector fault

    Oil-soaked connectors and chafed wires near the flywheel or pulley.

Step-by-step diagnostic guide

  1. 1

    Read codes and check rpm while cranking

    Read all codes. While cranking, check whether the scan tool or rev counter shows engine speed – no rpm while cranking points strongly to the crankshaft signal.

  2. 2

    Measure the signal voltage

    With the ignition on and the crankshaft position sensor plugged in, back-probe the signal wire. Then unplug it and check the reference/supply and ground wires separately.

    Multimeter: Signal near 0 V = short to ground or no reference. Reference wire: about 5 V with ignition on. Signal wire to ground with connector unplugged: no continuity.

  3. 3

    Inspect the sensor and tip

    Remove the sensor and look for debris, damage or oil in the connector. Clean the tip and check that it sits correctly.

  4. 4

    Measure the sensor

    Check supply and ground on Hall sensors; measure resistance and AC output on inductive sensors.

    Multimeter: Inductive sensors: often a few hundred to about 1,000 Ω and an AC voltage of roughly 0.5 V or more while cranking. Hall sensors: 5 V or 12 V supply and a switching square-wave signal.

  5. 5

    Check signal quality

    With an oscilloscope, look for missing, distorted or irregular teeth. A damaged reluctor ring shows as a repeating error at the same position.

  6. 6

    Replace and relearn

    Replace the sensor or repair wiring. Some engines need a crankshaft variation relearn (see P0315) after replacement.

Frequently asked questions

Can I keep driving with P0337?

Not recommended. A failing crankshaft sensor can make the engine stall without warning – including in traffic – and it may not restart.

How much does it cost to fix P0337?

Typical repair costs are 30 € – 400 €, depending on the cause and the vehicle. The most common fixes are: signal or control wire shorted to ground; missing 5 V reference or supply voltage; internal short in the crankshaft position sensor. Always confirm the cause with the tests above before buying parts.

Can a car start with a bad crankshaft sensor?

Usually not. Some engines can use the camshaft signal as a backup and start after long cranking, but most will not run without a crankshaft signal.

What is the difference between crankshaft and camshaft sensors?

The crankshaft sensor gives engine speed and piston position; the camshaft sensor tells which stroke the cylinder is on. The engine needs both for precise injection and ignition, but the crankshaft signal is the more critical.

What is the difference between P0337 and similar codes?

P0337 belongs to a group of codes for the same component that differ in the type or location of the fault: P0335 – Crankshaft Position Sensor A Circuit Malfunction; P0336 – Crankshaft Position Sensor A Circuit Range/Performance; P0338 – Crankshaft Position Sensor A Circuit High Input; P0339 – Crankshaft Position Sensor A Circuit Intermittent; P0370 – Timing Reference High Resolution Signal A Malfunction; P0371 – Timing Reference High Resolution Signal A Too Many Pulses. The tests on this page apply to the whole group; the type of fault tells you where to start.

Related fault codes

This guide is for information only. Working on vehicles can be dangerous — if you are unsure, have the car checked by a qualified mechanic. Values can differ between model years; always check the manufacturer's repair information.