P0388 code meaning
Crankshaft Position Sensor B Circuit High
Powertrain system Generic code P03xx codes Check engine light
What P0388 means
Some engines have a second crankshaft sensor or a second track on the tone wheel – GM's 3.4/3.5/3.8-litre V6 use the low resolution track of a dual Hall sensor, the Honda 3.5-litre in the Saturn Vue Redline a second sensor – which the engine module checks against sensor A or the camshaft. By its J2012 name P0388 means the signal of sensor B stays above its upper limit – with a Hall sensor typically an open signal wire held high by the module's pull-up, or a short to positive. No manufacturer document available to us uses P0388: the engines with a sensor B report its electrical faults under P0385 and implausible signals under P0386. The description therefore follows the J2012 name, these component sources and CARB's monitoring requirement for crank angle sensors. The engine usually keeps running on sensor A; longer cranking is possible.
P0388 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0388
- Check engine light on
- Longer cranking or starting problems
- Possibly rough running or misfire
- Often no noticeable symptoms while sensor A takes over
Common causes of P0388
- Most likelySignal wire of sensor B open or connector corroded or loose
- PossibleSignal wire shorted to positive or reference voltage
- PossibleSensor ground open
- PossibleSensor B faulty internally
- Less likelyEngine module input
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Crankshaft position sensor bCrankshaft tone wheelSensor wiringEngine control module
What each part of P0388 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 3 | Area: ignition system or misfire. |
| 88 | The exact fault in that area. |
What to do next
- Note P0388 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0388
What does P0388 mean?
P0388 means "Crankshaft Position Sensor B Circuit High". Some engines have a second crankshaft sensor or a second track on the tone wheel – GM's 3.4/3.5/3.8-litre V6 use the low resolution track of a dual Hall sensor, the Honda 3.5-litre in the Saturn Vue Redline a second sensor – which the engine module checks against sensor A or the camshaft. It is a generic code, so it means the same on every make.
Is it safe to drive with P0388?
Drive gently and only to a workshop. With P0388 the car can go into limp mode (reduced power) to protect itself.
Will P0388 fail an emissions test?
Yes, it can. P0388 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0388 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0388 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.