P2AC9
- Powertrain
- Manufacturer-specific
Diagnose soon
Usually safe to drive short distances, but the fault will not clear itself and can worsen or fail an emissions test.
Charge Air Cooler Coolant Temperature Sensor B Circuit Low
This code is in our catalogue but has not yet been through editorial review, so the guidance below is limited to what our structured data supports. We publish deeper diagnostic content only after a code has been reviewed — here is why.
Voltage on the charge air cooler coolant temperature B sensor signal line is below the expected window. Wire shorted to ground or sensor short.
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Usually safe to drive short distances, but the fault will not clear itself and can worsen or fail an emissions test.
- Urgency
- Diagnose soon
- Will it pass emissions
- Not affected
- Check engine light
- Solid
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | Signal wire shorted to ground | Very common | — |
| 2 | Internal sensor short | Common | — |
| 3 | Connector pins corroded - high contact resistance | Occasional | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
- Charge Air Cooler Coolant Temp Sensor B
- Wiring Harness
- ECM
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Awaiting review
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