Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Code P0337/338, Crank Sensor Input - "S" & "T" Series 4.3L (VIN W): Notes
Crankshaft position sensor sends a toggling (0-5 volt) voltage signal to control module to indicate crankshaft position and RPM. Control module uses this signal to determine when pulse ignition coil and control timing. Code will set if duty cycle ratio is low (Code P0337) or high (Code P0338).
- Determines if code is hard or intermittent.
- Checks for low duty cycle.
- Determines if voltage is available to sensor through control module.
- If feed circuit is shorted to ground, test light will be on. This determines if circuit is open or shorted to ground.
- Checks crankshaft sensor, signal circuit and control module.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.