P0073🔧 Ambient (outside) air temperature sensorDrive with caution, fix soon

P0073: Ambient Air Temperature Sensor Circuit High (Meaning, Causes, Fixes)

Reviewed 2026-10-23 · Based on 2 cited source(s)

What P0073 means

The ambient air temperature (AAT) sensor measures the outside air temperature. OBD-Codes.com says the reading is used to adjust air conditioning operation and to show the outside temperature on the dash, and that the PCM (engine computer) compares the AAT reading with the intake air temperature (IAT) and engine coolant temperature (ECT) sensors when the car is first started after a long cool-down, and checks the signals again once the engine is fully warm. RepairPal describes a different use, saying the sensor helps the PCM decide how much fuel to use on startup and serves as a reference for the other engine temperature sensors. The sources also describe the trigger differently. OBD-Codes.com's article says the code sets when these sensor inputs vary too much, which reads more like a range/performance check, though its listed causes (an open circuit or a short to voltage in the signal wire) fit a signal that is too high. RepairPal only says the code sets when the PCM detects an issue with the sensor's signal. OBD-Codes.com notes that on some vehicles the sensor feeds a different module, such as the air conditioning control module, which shares the reading over the vehicle network. It is a generic code, and OBD-Codes.com says it shows up more often on certain Audi, BMW, Chrysler, Dodge, Ford, Jeep, Mazda, Mitsubishi and VW vehicles. Related codes in the same family are P0070 (circuit), P0071 (range/performance), P0072 (circuit low) and P0074 (circuit intermittent).

Severity: can I keep driving?

Drive with caution, fix soon

Usually safe to drive, but get it diagnosed soon. RepairPal rates P0073 Moderate, meaning it may not threaten safety right away but should be checked within a reasonable time. OBD-Codes.com gives no severity rating and lists mostly comfort symptoms, such as air conditioning that may not work properly and a wrong outside temperature reading. RepairPal also lists hard starting, so if the engine becomes hard to start or runs poorly, have it checked sooner.

Common symptoms

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

  1. Bad connections at the sensor, such as corroded or burned terminals; OBD-Codes.com calls this the most common failure (OBD-Codes.com, RepairPal lists wiring issues)
  2. Faulty ambient air temperature sensor, a close second because of its exposed location (OBD-Codes.com, RepairPal)
  3. Open circuit or short to voltage in the sensor's signal wire (OBD-Codes.com)
  4. Faulty engine computer (PCM), which OBD-Codes.com calls unlikely (OBD-Codes.com, RepairPal)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

  1. Check for technical service bulletins (TSBs) for your vehicle first (OBD-Codes.com).
  2. Find the sensor, usually in front of the radiator behind the grille or front bumper, and inspect the wiring for rubbing, bare wires, burn spots or melted plastic (OBD-Codes.com).
  3. Unplug the connector and look for burned or green, corroded terminals. OBD-Codes.com suggests electrical contact cleaner and a plastic bristle brush, then electrical grease once dry.
  4. Clear the code and see if it returns. If it doesn't, the connection was most likely the problem (OBD-Codes.com).
  5. With a multimeter and the ignition off, measure the sensor's resistance and compare it with your service manual's chart for the current outside temperature. OBD-Codes.com says 0 ohms or an open reading (OL) means the sensor has failed.
  6. With a scan tool, OBD-Codes.com describes unplugging the sensor (the reading should go to about 5 volts or a very low temperature) and then jumping the two harness terminals (it should drop near 0 volts or a very high temperature). No 5 volts or no change points to wiring or a control module; values and the module that reads the sensor vary by vehicle.

Typical fixes

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

  • You don't have a multimeter, scan tool or the resistance chart for your sensor
  • The code returns after a new sensor and repaired connections
  • There's no 5-volt reference at the sensor connector
  • Your vehicle reads the sensor through a module other than the PCM and you aren't sure which
  • The engine is hard to start or runs poorly along with the code

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Can I drive with P0073?

Usually yes for a short time. RepairPal rates it Moderate and OBD-Codes.com lists mainly air conditioning and outside temperature display symptoms, but get it diagnosed soon, especially if the engine is hard to start.

Why is my outside temperature reading wrong with P0073?

The dash display relies on the same ambient air temperature sensor. If the sensor or its wiring has failed, OBD-Codes.com says the instrument cluster or overhead console may not show the outside temperature accurately.

Can P0073 affect my air conditioning?

It can. OBD-Codes.com says the sensor's reading is used to adjust air conditioning operation, so the A/C may not perform properly while the code is set.

How much does it cost to fix P0073?

Neither source gives a repair cost for P0073. It can be as simple as cleaning a corroded connector or as involved as replacing the sensor or repairing wiring, so diagnose it first.

Sources

  1. OBD-Codes.com: P0073 Ambient Air Temperature Sensor Circuit High
  2. RepairPal: P0073 Ambient Air Temperature Sensor Circuit High (rated Moderate)

Last reviewed 2026-10-23. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.