Turbo/Supercharger Boost Sensor B Circuit Intermittent
The P0239 code means the vehicle's onboard diagnostic system has detected: Turbo/Supercharger Boost Sensor B Circuit Intermittent. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $80 - $350 (parts and labor)
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Common Symptoms
- Check Engine Light on intermittently
- Boost pressure readings fluctuate unexpectedly
- Intermittent power loss under boost
- Boost may cut in and out
Probable Causes (Ranked by Likelihood)
- Loose boost sensor B connector Very High
- Intermittent wire break in sensor circuit High
- Failing sensor with inconsistent output Moderate
- Vibration-induced connection fault Low
Step-by-Step Diagnostic Procedure
-
Monitor boost sensor B on scan tool while tapping connector and wiggling wires. Watch for signal dropouts.
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Inspect connector for loose pins, corrosion, or poor seating.
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Check wiring at stress points for intermittent breaks.
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If wiring is good, replace the boost pressure sensor.
Frequently Asked Questions
Why is my boost intermittent?
An intermittent electrical connection to the boost sensor causes the PCM to lose the boost pressure reading momentarily, which triggers boost safety cuts.
Can engine vibration cause P0239?
Yes, normal engine vibration can worsen a marginal connector or cracked wire, causing intermittent signal loss.
How do I diagnose an intermittent boost sensor fault?
Use the wiggle test: monitor the sensor reading live while manipulating the connector and wiring. The reading will jump when you find the fault location.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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