Can you keep driving?
Can you keep driving?
Stop driving if any of these apply
- !The engine stalls, cranks without starting, or cuts out repeatedly.
- !The tachometer drops out or the warning light flashes while driving.
What to check first
Step-by-step checks
- 1
Free - no tools
Inspect the connector and harness for heat damage, oil contamination, or rubbed-through insulation
- 2
Free - no tools
Check whether the code appears after heat soak or rough driving conditions
- 3
Basic tool needed
If scan data is available, confirm whether the RPM signal looks implausibly high or noisy
- 4
Basic tool needed
Look for recent timing work that may have changed sensor gap or trigger alignment
- 5
Basic tool needed
If the signal jumps around with a harness wiggle, the wiring side needs attention first
If the code returns
- -If the signal is still too high after wiring checks, the sensor or trigger path becomes more likely.
- -If the code returns after a replacement, verify the sensor gap and mounting before moving on.
- -If the engine is still running badly, treat that as a separate clue rather than a sensor-only issue.
Background
What this code means
P0338 is a generic OBD-II crankshaft-speed or engine-speed input code for crankshaft position sensor A.
A high crank signal can come from wiring, sensor bias, or a trigger pattern that is not what the ECU expects.
The engine may stall, misfire, or become hard to restart when the speed signal is distorted enough to affect timing control.
Diagnosis
Common causes
Biased crank sensor
The ECU may be seeing a signal that is outside the expected range.
Connector or wiring issue
A pin fit or insulation problem can distort the signal.
Trigger wheel or alignment issue
A mechanical timing input issue can produce the wrong pattern.
Heat or oil damage
Contamination can change the signal quality enough to trigger the code.
Avoid these mistakes
What not to do
- xDo not keep cranking a no-start engine for a long time if the speed signal is missing.
- xDo not replace the ECU before checking the crank sensor, connector, and wiring.
Parts
Parts that may need replacing
See also
Related OBD codes
P0335
P0335 usually means the crankshaft position sensor A circuit is not behaving correctly.
P0336
P0336 usually means the crankshaft position sensor A signal is out of normal range or performance.
P0337
P0337 usually means the crankshaft position sensor A signal is reading too low.
P0339
P0339 usually means the crankshaft position sensor A signal is intermittent.
Source notes
Generic OBD-II (SAE J1979 / ISO 15031-5). P0338 was expanded around common high crankshaft-position sensor faults, including sensor bias, wiring issues, and trigger-wheel problems.
This guide is written as a generic multi-make reference, so bulletin history, sensor locations, and repair order can still change by manufacturer and engine family.
This is generic OBD-II guidance and should not override vehicle-specific service information. Exact diagnosis and repair steps vary by make, engine family, and model year.
Last reviewed: 2026-04-10
Reference: Open reference