OBD-II Code · Powertrain
P0337
Crankshaft Position Sensor A Circuit Low
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Not for long
Driving on this one risks further damage. Get it to a shop rather than carrying on with it.
Indicative cost (USD)
$140–$480
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
CKP signal voltage stuck below threshold.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Hot crank-no-start
- Stumble at hot restart
- Check engine light
Likely causes
- Weak sensor signalMost common
- Wire resistance
- Dirty sensor ground
- Heat-soaked CKP
Read the full diagnostic procedureP0337 means the CKP signal voltage is stuck below the ECM's low-threshold limit — typically below 0.5V on a Hall-effect signal that should be swingin…
P0337 means the CKP signal voltage is stuck below the ECM's low-threshold limit — typically below 0.5V on a Hall-effect signal that should be swinging 0-5V, or a VR signal that is producing less than 200 mV peak-to-peak at cranking. The signal is present electrically but too weak to count as valid pulses.
Cheapest-first ladder
- back-probe the signal wire at the ECM connector (not the sensor) and scope it during cranking — if the signal is healthy at the sensor but weak at the PCM, you have wire resistance somewhere in between.
- Measure signal-wire resistance end-to-end (should be under 5 ohms for a 6-foot run); anything over 10 ohms means corroded pins or a damaged conductor.
- Check for poor sensor ground — back-probe the sensor ground pin and measure to battery negative with key on (should be under 50 mV; over 200 mV means the ground path is dirty).
- Inspect the sensor tip for oil contamination or accumulated debris that increases the effective air gap and drops signal amplitude.
- The expensive misdiagnosis is replacing the sensor and PCM when the actual fault is a green crusty C1 main engine harness connector behind the alternator.
Vehicle-specific patternsBMW N54 (2007-2010 335i, 535i, 1M, Z4) is the textbook P0337/P0335 hot-start failure — the CKP sensor fails only after heat-soak, will start fine col…
BMW N54 (2007-2010 335i, 535i, 1M, Z4) is the textbook P0337/P0335 hot-start failure — the CKP sensor fails only after heat-soak, will start fine cold, then crank-no-start after a 10-minute restaurant stop, then start fine again after cooling. Replace the sensor and the connector pigtail together because the heat also degrades the connector seal. Nissan VQ35DE (Altima, Maxima, Pathfinder 2002-2008) loses CKP signal amplitude as the sensor magnetics weaken from exhaust-heat aging — bench-test will show a sensor that ohms in-spec cold but produces 60% of normal output hot. GM 3.6L LY7/LLT throws P0337 when the CKP pigtail melts against the exhaust manifold heat shield on high-mileage units. Honda K24 (2003-2011 Accord, Element, CR-V) Hall-effect CKP loses amplitude as the internal IC degrades from underhood heat cycling.
Estimated repair$140 to $480.
Look up another code
P0337 — frequently asked
What does a P0337 code mean?
CKP signal voltage stuck below threshold.
What causes a P0337 code?
Common causes: Weak sensor signal; Wire resistance; Dirty sensor ground; Heat-soaked CKP.
What are the symptoms of a P0337 code?
Typical symptoms: Hot crank-no-start; Stumble at hot restart; Check engine light.
Is it safe to drive with a P0337 code?
Not for long. Driving on this one risks further damage. Get it to a shop rather than carrying on with it. Estimated repair: $140-$480.
How do I diagnose a P0337 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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