An open circuit in the signal wire between the ambient air temperature sensor and the module, often from a broken wire in the front bumper harness.; A failed ambient air temperature sensor whose internal thermistor has gone open or drifted to a very high resistance.; Corroded or pushed-back terminals at the sensor connector or at the module connector, creating a high-resistance connection.; A poor ground connection on the sensor return circuit, which can make the signal voltage float high.; Damage to the sensor or its wiring from road debris, a minor impact, or rodent chewing in the front of the vehicle.; A faulty module that is misreading the circuit, though this is the least likely cause and should only be suspected after all wiring and sensor checks pass.

DTC codes / P00xx · Fuel and air metering and auxiliary emission controls / P00DC

P00DCAmbient Air Temperature Sensor Circuit B High

Q: What does code P00DC mean?

Ambient Air Temperature Sensor Circuit B High. P00DC indicates that the powertrain control module has detected an abnormally high voltage signal on the ambient air temperature sensor circuit, which is the sensor that reports outside air temperature to the engine computer. The circuit is typically a two-wire design where the sensor is a thermistor that varies resistance with temperature, and a high voltage reading means the signal wire is seeing near-reference voltage, usually because the circuit is open or the sensor resistance has gone very high.

P00DC indicates that the powertrain control module has detected an abnormally high voltage signal on the ambient air temperature sensor circuit, which is the sensor that reports outside air temperature to the engine computer. The circuit is typically a two-wire design where the sensor is a thermistor that varies resistance with temperature, and a high voltage reading means the signal wire is seeing near-reference voltage, usually because the circuit is open or the sensor resistance has gone very high.

SystemPowertrain

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaFuel and air metering and auxiliary emission controls

Symptoms you may notice

Often no symptoms besides the warning light, because the ambient temperature reading is not used for engine fueling on many vehicles.
An outside temperature display that reads blank, dashes, or a fixed extreme value such as -40 degrees.
Climate control system that blows the wrong temperature or fails to switch between fresh and recirculated air correctly.
Remote start or battery management features that refuse to operate because the module cannot confirm a safe ambient temperature.
A secondary code for the same sensor circuit stored in a body or climate control module, since the ambient sensor is often shared across networks.
In rare cases, a slight effect on cold-start idle quality or fuel economy if the PCM uses ambient temperature for cold-start enrichment correction.

Common causes, most likely first

An open circuit in the signal wire between the ambient air temperature sensor and the module, often from a broken wire in the front bumper harness.
A failed ambient air temperature sensor whose internal thermistor has gone open or drifted to a very high resistance.
Corroded or pushed-back terminals at the sensor connector or at the module connector, creating a high-resistance connection.
A poor ground connection on the sensor return circuit, which can make the signal voltage float high.
Damage to the sensor or its wiring from road debris, a minor impact, or rodent chewing in the front of the vehicle.
A faulty module that is misreading the circuit, though this is the least likely cause and should only be suspected after all wiring and sensor checks pass.

How to diagnose and fix it

Connect a scan tool and read the ambient air temperature sensor value in live data to confirm it is stuck at an extreme high or low reading that does not change with actual temperature.
Visually inspect the sensor and its connector at the front of the vehicle for physical damage, corrosion, or loose pins, and repair any obvious wiring faults.
Disconnect the sensor and measure its resistance with a multimeter, then compare the reading to the expected value for the current ambient temperature from a resistance chart.
Check the signal wire for continuity from the sensor connector to the module connector and check for short to voltage or short to ground on the same wire.
Check the sensor ground circuit for continuity to chassis ground and repair any high-resistance ground connection.
If the wiring and ground are good but the sensor resistance is out of specification, replace the ambient air temperature sensor and clear the code.
After repair, clear the diagnostic trouble codes and verify the live data reading tracks actual ambient temperature as the vehicle sits and after a cold soak.

Ambient sensor faults that fool good technicians

The ambient air temperature sensor is frequently shared between the powertrain control module and the climate control module, so a code in one module can be caused by a fault that the other module also reports, and checking both modules saves time.
A sensor that reads correctly at room temperature can still set P00DC intermittently when the vehicle is cold, because the thermistor resistance curve goes very high at low temperatures and a marginal connection will open up.
Many vehicles use the ambient temperature reading to inhibit remote start or to control the fresh air door, so a driver may complain about those features without ever mentioning the temperature display.
Rodent damage to the front bumper harness is a common cause that is missed when the technician only checks the sensor itself, so a careful visual inspection of the whole harness run is essential.
Do not replace the module until you have loaded the circuit with a resistor substitution box or a known-good sensor to prove the wiring is not the problem, because module replacement is expensive and rarely the real fix.

Can I keep driving with P00DC?

This code is safe to drive with in most cases because the ambient air temperature signal is not critical to engine operation, but you should avoid relying on remote start or automatic climate features until it is repaired. Have the circuit inspected soon if you notice the outside temperature display is wrong, since a wiring fault can spread to other circuits in the same harness.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.