P0072🔧 Ambient (outside) air temperature sensorDrive with caution, fix soon

P0072: Ambient Air Temperature Sensor Circuit Low (Meaning, Causes, Fixes)

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

What P0072 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, while RepairPal only says the code sets when the PCM detects an issue with the sensor's signal. There is also a mismatch inside OBD-Codes.com's article: it lists an open in the signal or ground circuit as causes, but its own scan-tool test says an unplugged (open) sensor circuit should read about 5 volts, a very low temperature, while jumping the two harness wires together should read close to 0 volts, a very high temperature. So for a low reading, a short between the sensor wires or to ground is worth checking along with the listed causes. 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, VW and Volvo vehicles. Related codes in the same family are P0070 (circuit), P0071 (range/performance), P0073 (circuit high) 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 P0072 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 in the sensor's signal or ground circuit (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 scraping, 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 P0072?

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 P0072?

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.

What's the difference between P0072 and P0073?

Both point to the ambient air temperature sensor circuit. P0072 means the signal is reading low and P0073 means it is reading high. OBD-Codes.com's tests show a low voltage corresponds to a very high temperature reading, and an open circuit reads about 5 volts.

How much does it cost to fix P0072?

Neither source gives a repair cost for P0072. 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: P0072 Ambient Air Temperature Sensor Circuit Low
  2. RepairPal: P0072 Ambient Air Temperature Sensor Circuit Low (rated Moderate)

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