P0074 code meaning
Ambient Air Temperature Sensor Circuit A Intermittent/Erratic
Powertrain system Generic code P00xx codes Check engine light
What P0074 means
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. P0074 is set when the signal jumps or is noisy, i.e. changes faster than a real temperature can, which typically points to a loose contact.
P0074 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1 hours
- Clears after repairAfter a drive cycle
Symptoms of P0074
- Outside temperature display jumps
- Climate control regulates incorrectly
- Check engine light on (manufacturer-dependent)
- Other monitors may not complete
Common causes of P0074
- Most likelyLoose contact or corrosion at the connector
- PossibleWire broken inside the harness
- PossibleSensor faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ambient air temperature sensorAmbient air temperature sensor wiringInstrument cluster
What each part of P0074 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| 74 | The exact fault in that area. |
What to do next
- Note P0074 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0074
What does P0074 mean?
P0074 means "Ambient Air Temperature Sensor Circuit A Intermittent/Erratic". The ambient air temperature sensor A is an NTC thermistor whose resistance falls as temperature rises. It is a generic code, so it means the same on every make.
Is it safe to drive with P0074?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0074 fail an emissions test?
Yes, it can. P0074 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0074 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0074 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.