What it means
Generic electrical fault on ambient air temperature sensor B (second sensor for redundancy or second measurement location).
At a glance
- Usually lights the check-engine light
How it works
Ambient air temperature sensor B measures outside air at its particular sensing location, which may be separate from sensor A. The control module monitors sensor B's electrical circuit and sets P00D9 when the circuit does not behave as expected; this general circuit fault does not by itself identify a low, high, or intermittent signal.
Common causes
Most likely first.
- Failed ambient air temperature sensor B
- Damaged wiring or poor connector contact
- Open or short in the sensor circuit
Symptoms
- Check-engine light on
- Outside-temperature display may be inaccurate
- Climate control may respond incorrectly
How to diagnose it
- Check freeze-frame data and live readings for ambient temperature sensor B, and compare them with the displayed outside temperature and conditions around the vehicle.
- Locate sensor B using vehicle service information and inspect its connector and wiring for corrosion, looseness, damage, or water entry.
- Check whether live data changes plausibly as the sensor and surrounding air temperature change.
- Test the sensor B circuit for an open, short, or poor connection using the manufacturer's wiring information.
- If wiring and connections are sound, test sensor B against the manufacturer's specification and replace it if it fails.
Common fixes
- Clean and secure the sensor B connector if contact is poor.
- Repair an open, short, or damaged wire in the sensor B circuit.
- Replace a faulty ambient air temperature sensor B.
Can I keep driving?
This fault usually affects the outside-temperature display or climate control rather than engine operation, so normal driving is generally possible. Have it diagnosed if inaccurate temperature readings interfere with climate control or the warning light is accompanied by other symptoms.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.