Ambient air temperature sensor B is a second, separate ambient temperature circuit in addition to sensor A. What the second measuring point is used for in a given vehicle could not be documented; the value may be wired directly to the control module or come over the data bus. Regulations require monitoring of such inputs because ambient temperature is often an enabling condition for other diagnostics. None of the manufacturer documents searched uses these codes; the explanation follows sensor A. P00D9: This is the general circuit fault or an invalid signal.
Low severity. Can I keep driving?Yes, you can normally keep driving and take it to a repair shop when convenient.
Symptoms
- Wrong or missing outside temperature display
- Climate control regulates incorrectly
- Check engine light on (manufacturer-dependent)
Most likely causes
- Sensor faulty (exposed to spray and stone chips)
- Connector corroded or wiring damaged, often after front-end work
- Module supplying the value over the data bus faulty
- Control module faulty
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: easy
- It affects emissions.
What each character of P00D9 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 0: Subsystem depends on the code range
- D9: Specific fault in that system
Frequently asked questions
Can I keep driving with code P00D9?
Yes, you can normally keep driving and take it to a repair shop when convenient.
What causes code P00D9?
The most common causes are: sensor faulty (exposed to spray and stone chips); connector corroded or wiring damaged, often after front-end work; module supplying the value over the data bus faulty.
Related codes
- P00DAAmbient Air Temperature Sensor Circuit B Range/Performance
- P00DBAmbient Air Temperature Sensor Circuit B Low
- P00DCAmbient Air Temperature Sensor Circuit B High
- P00DDAmbient Air Temperature Sensor Circuit B Intermittent/Erratic
- P0070Ambient Air Temperature Sensor Circuit A
Sources
- law.cornell.edu: 13 CCR 1968.2
- gsi.ext.gm.com: 16OBDG04 Engine Diagnostics
- fordservicecontent.com: OBD Operations Summary Gasoline 2020 2023
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.