Cylinder Pressure Sensor Circuit High (Bank 1)
The P0398 code means the vehicle's onboard diagnostic system has detected: Cylinder Pressure Sensor Circuit High (Bank 1). This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $200 - $800 (parts and labor)
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Common Symptoms
- Check Engine Light on
- Excessive timing retard
- Reduced performance
- Possible limp mode
Probable Causes (Ranked by Likelihood)
- Open circuit in pressure sensor wiring Very High
- Failed sensor (open) High
- Disconnected connector Moderate
- Short to reference voltage Low
Step-by-Step Diagnostic Procedure
-
Read sensor voltage. Above maximum spec confirms high circuit.
-
Check connector.
-
Test wiring continuity.
-
Replace sensor if open.
Frequently Asked Questions
What does circuit high mean for the pressure sensor?
The PCM sees a voltage above maximum, usually from an open wire or disconnected sensor.
Will the engine enter limp mode with P0398?
Some vehicles will reduce power when cylinder pressure monitoring is unavailable, as a protection against knock damage.
Is this sensor replaceable?
Yes, cylinder pressure sensors are replaceable components, though they can be expensive ($100-$400 per sensor).
Sources
This page is built from documented references. Verify against your own service info before repair work.
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