Failed crankshaft position sensor (internal open circuit or damaged windings); Open or damaged signal wire between the sensor and the engine computer; Corroded, loose, or pushed-back terminal in the sensor or computer connector; Signal wire shorted to a power source or chafed against a hot or moving component; Missing or damaged reluctor wheel teeth or excessive sensor air gap; Electrical interference from a faulty ignition component or poor ground; Rarely, a failed engine computer input circuit

DTC codes / P03xx · Ignition system and misfire / P0338

P0338Crankshaft Position Sensor A Circuit High Input

Q: What does code P0338 mean?

Crankshaft Position Sensor A Circuit High Input. P0338 means the engine computer has detected an abnormally high voltage on the signal circuit from the crankshaft position sensor, which it uses to determine engine speed and piston position. The sensor normally produces a fluctuating AC signal or a square wave, and a high input tells the computer the circuit is open, shorted to power, or the sensor has failed internally.

P0338 means the engine computer has detected an abnormally high voltage on the signal circuit from the crankshaft position sensor, which it uses to determine engine speed and piston position. The sensor normally produces a fluctuating AC signal or a square wave, and a high input tells the computer the circuit is open, shorted to power, or the sensor has failed internally.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Engine cranks but will not start, or starts and immediately stalls
Intermittent stalling while driving, especially when the engine is hot or over bumps
Misfire, rough running, or loss of power under acceleration
Tachometer needle drops to zero or behaves erratically
Often no symptoms besides the warning light if the fault is intermittent

Common causes, most likely first

Failed crankshaft position sensor (internal open circuit or damaged windings)
Open or damaged signal wire between the sensor and the engine computer
Corroded, loose, or pushed-back terminal in the sensor or computer connector
Signal wire shorted to a power source or chafed against a hot or moving component
Missing or damaged reluctor wheel teeth or excessive sensor air gap
Electrical interference from a faulty ignition component or poor ground
Rarely, a failed engine computer input circuit

How to diagnose and fix it

Inspect the sensor connector and wiring for corrosion, chafing, or loose pins, and repair as needed
Check the sensor air gap and reluctor wheel condition if the sensor is a magnetic type
Measure sensor resistance and compare to the manufacturer's specification
Back-probe the signal circuit with a multimeter or oscilloscope while cranking to confirm the high voltage is real
Check for a short to power on the signal wire with the sensor disconnected
Replace the crankshaft position sensor if the circuit and wiring test good but the signal remains high
Clear the code and verify the repair with a road test and live data

What a high crankshaft signal really means

A high input often indicates an open circuit rather than a shorted sensor, so a broken wire or unplugged connector is a common culprit that gets missed when the sensor is replaced first.
Some engines will run with a failed crankshaft sensor by using the camshaft sensor as a backup, so the only symptom may be a hard-start or a stored code with no drivability complaint.
Debris or metal shavings stuck to a magnetic crankshaft sensor can distort the signal and set a high-input code without any wiring fault.
A weak or failing battery or a poor engine ground can cause voltage spikes that the computer interprets as a high crankshaft signal, so check the charging system before condemning the sensor.
After replacing the sensor, the crankshaft position variation learn procedure may be required on some vehicles to prevent a repeat code or rough running.

Can I keep driving with P0338?

If the engine starts and runs normally, you can drive cautiously to a repair shop, but avoid long trips and high-speed driving. If the engine stalls, misfires badly, or will not restart, stop driving and have the vehicle towed because a failed crankshaft sensor can cause a sudden stall with no warning.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.