P0388 Code Meaning and Next Steps

First checks take 10 minutes for basic checks. No special tools are usually needed for the first checks.

Can you keep driving?

Stop driving if any of these apply

!The check-engine light is flashing or the engine is shaking badly.
!The vehicle is stalling, struggling to accelerate, or obviously running rough.

If the light is steady and the vehicle still drives normally: Maybe, but only for a very short distance if the engine still runs smoothly.

What to check first

Step-by-step checks

1
Free - no tools
Check whether the engine has a hard-start, stall, or rough-run symptom with the code
2
Free - no tools
Inspect the sensor connector and harness for oil, heat, or abrasion damage
3
Basic tool needed
Look for related crankshaft, camshaft, or misfire codes that may help with diagnosis
4
Basic tool needed
If scan data is available, compare crank signal stability with engine RPM behavior
5
Basic tool needed
Notice whether the code appeared after timing work or sensor replacement

If the code returns

-If the signal is too high at the sensor, the sensor or tone wheel becomes more likely.
-If the signal looks okay but the engine still has timing problems, inspect the mechanical side.
-If the code returns after connector repair, recheck sensor fit and wiring routing.

Background

What this code means

P0388 is a generic OBD-II code for a high crankshaft position sensor B signal.

The engine controller is seeing a signal that is too high for the condition or not trustworthy. The issue may be electrical, mechanical, or related to the sensor gap and mounting.

Diagnosis

Common causes

Most common

Failed crankshaft position sensor B

The sensor may be producing an implausibly high signal.

Common

Wiring or connector damage

Heat, oil, or corrosion can skew the signal.

Common

Damaged tone wheel

The reference pattern may be distorted and read too strongly.

Possible

Sensor gap or mounting issue

A poor gap or loose mount can make the signal look high.

Avoid these mistakes

What not to do

xDo not replace the ECU first if the sensor or tone wheel is visibly damaged.
xDo not ignore stalling or no-start symptoms that line up with the crank signal fault.

Parts

Parts that may need replacing

PartTypical costNotes

Crankshaft position sensor B$40-$180Worth checking when the crank signal is implausibly high.

Connector or wiring repair$50-$250Useful when the circuit is contaminated or intermittent.

Tone wheel or reluctor repair$200-$900Relevant when the mechanical reference pattern is damaged.

Related OBD codes

P0385

P0385 means the crankshaft position sensor B circuit has a malfunction.

P0386

P0386 means the crankshaft position sensor B signal is out of range or not believable.

P0387

P0387 means the crankshaft position sensor B signal is too low or missing.

Source notes

Generic OBD-II (SAE J1979 / ISO 15031-5). P0388 was seeded from dtcdb and then expanded around crankshaft position sensor B high-input faults, with emphasis on sensor, wiring, and tone-wheel checks.

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

P0388 - The Crankshaft Position Sensor B Signal Is Too High