P0337
Crankshaft Position Sensor A Circuit Range/Performance
Powertrain Ignition System CKP sensor signal loss/degradation 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

The crankshaft position sensor tells your engine's computer where the crankshaft is spinning, like a tachometer for precise timing. When this sensor's signal is weak, erratic, or out of range, the ECU can't properly control ignition and fuel injection.

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Symptoms You May Notice
3 known symptoms for this code
Engine cranks but won't start or starts then stalls immediately
Severe hesitation, misfires, or rough idle
Check Engine Light illuminated
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECM monitors the crankshaft position sensor signal voltage and frequency as the engine cranks and runs. It expects a clean, consistent AC or digital signal within specific voltage and timing parameters. If the signal drops below minimum voltage, becomes erratic, or loses sync with expected crank speed, the ECU triggers P0337.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Sensor signal voltage 0.2–5.0 V (varies by sensor type) Below 0.2 V or above 5.5 V; intermittent dropout
Signal frequency/duty cycle stability Smooth, predictable pulse pattern matching RPM Erratic, missing teeth, or out-of-sync with actual crank speed
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Crankshaft position sensor connector
Inspect and reseat the CKP sensor connector; clean any corrosion on pins with contact cleaner.
2
Crankshaft position sensor wiring harness
Check the sensor wiring for cracks, abrasion, or loose connections along the entire length; repair or resolder as needed.
3
Crankshaft position sensor
Replace the sensor if voltage testing shows low or no signal output at the connector with the engine cranking.