P0070Ambient Air Temperature Sensor Circuit A
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- The ambient air temperature sensor A is an NTC thermistor whose resistance falls as temperature rises. Its value is used by the climate control, the outside temperature display and the engine control module, which needs it to enable other diagnostics and to correct its maps. Depending on the vehicle the engine control module reads the sensor directly, or the instrument cluster or another module sends the value over the data bus; some vehicles have no sensor and estimate ambient temperature from intake air temperature. P0070 is the general circuit fault or an invalid signal, for example when the instrument cluster reports the value as invalid or the reading is implausibly low.
- What you may notice
- Wrong or missing outside temperature display
- Climate control regulates incorrectly
- Check engine light on (manufacturer-dependent)
- Other monitors may not complete
- Likely causes
- LikelySensor faulty (exposed to spray and stone chips at the front)
- LikelyConnector corroded or wire damaged, e.g. after front-end damage
- PossibleInstrument cluster or data transmission faulty (vehicles with bus-supplied value)
- RareEngine control module faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €40 – €200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.