Faulty ambient air temperature sensor (internal open or short circuit, or reading drifting); Damaged, corroded or loose sensor connector, often at the front bumper where it is exposed to water and road dirt; Chafed, broken or shorted wiring between the sensor and the control unit, including a short to ground or to voltage; Sensor physically damaged by a minor front-end impact or poorly refitted after bumper or grille work; Poor earth or reference supply shared with other sensors; Fault in the control unit that reads the sensor, or a data-sharing fault if the reading is received over the network (depends on the model).

P0070

Ambient Air Temperature Sensor Circuit A.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
0: AreaFuel and air metering, auxiliary emission controls
70: FaultThe specific fault in that area

What it means

P0070 is the generic code for a fault in the ambient air temperature sensor circuit. The control unit monitors the signal voltage from the outside air temperature sensor and sets the code when it sees a reading outside the expected range, or a value that is implausible compared with other temperature data. It is usually a wiring, connector or sensor problem rather than a serious mechanical fault.

Symptoms

Warning light on, or a stored fault with no obvious change in driveability
Outside temperature display on the dashboard showing dashes, a fixed value or an obviously wrong reading
Automatic climate control not holding the set temperature or behaving oddly
Slightly rough or slow cold starting on some models
Frost or ice warning appearing at the wrong time, or not at all

Possible causes

Faulty ambient air temperature sensor (internal open or short circuit, or reading drifting)likely
Damaged, corroded or loose sensor connector, often at the front bumper where it is exposed to water and road dirtlikely
Chafed, broken or shorted wiring between the sensor and the control unit, including a short to ground or to voltagepossible
Sensor physically damaged by a minor front-end impact or poorly refitted after bumper or grille workpossible
Poor earth or reference supply shared with other sensorsrare
Fault in the control unit that reads the sensor, or a data-sharing fault if the reading is received over the network (depends on the model)rare

How to diagnose

Read all stored codes and the freeze frame data, then note whether the fault is current, intermittent or historic
Compare the displayed ambient temperature with the real outside temperature and with the intake air and coolant temperatures on a cold car
Visually inspect the sensor, its mounting and the connector for damage, water, dirt and corrosion
Wiggle test the wiring and connector with live data on screen to see if the reading jumps
Unplug the sensor and check the signal and reference/earth circuits for open circuit, short to ground and short to voltage, using the wiring diagram for that model
Measure the sensor resistance and compare it with the manufacturer's temperature-resistance specification
Check where the sensor signal is read (engine, body or climate control unit) as this varies by model, and check for related network or control unit faults

How to fix

Replace the ambient air temperature sensor if its resistance is out of specification or readings are erratic
Clean, repair or replace the damaged or corroded connector terminals
Repair or replace the damaged wiring section, making sure it is routed and secured away from sharp edges and heat
Refit or secure the sensor correctly in its mounting position
Clear the code after repair and road test to confirm it does not return

Can I keep driving?

Low severity

The car is normally safe to drive with this code, as it mainly affects the temperature display and climate control. Book it in at your convenience, but be aware that the outside temperature display and ice warning may not be reliable.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.