OBD-II Code
P0072
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$15–$300
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
$15 (sensor swap DIY) to $300 (sensor + harness repair + connector).
P0072 is the specific ambient air temperature sensor circuit LOW INPUT fault — the PCM is seeing the AAT signal pinned at or below the low-voltage threshold (typically below 0.2-0.5V, which scales to a temperature reading at or below the -40 F floor of the sensor table), which physically means either the signal wire is shorted to ground, the sensor itself has failed open (a failed-open thermistor reads infinite resistance, which the PCM interprets as below-floor on some pull-up configurations) or shorted internally, or the sensor connector is unplugged.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP0072 is the specific ambient air temperature sensor circuit LOW INPUT fault — the PCM is seeing the AAT signal pinned at or below the low-voltage th…
P0072 is the specific ambient air temperature sensor circuit LOW INPUT fault — the PCM is seeing the AAT signal pinned at or below the low-voltage threshold (typically below 0.2-0.5V, which scales to a temperature reading at or below the -40 F floor of the sensor table), which physically means either the signal wire is shorted to ground, the sensor itself has failed open (a failed-open thermistor reads infinite resistance, which the PCM interprets as below-floor on some pull-up configurations) or shorted internally, or the sensor connector is unplugged.
Cheapest-first ladder
- Scan live data and confirm AAT is reading the -40 F floor value — if it is, you have a hard circuit fault, not a drift.
- Pull the AAT connector and inspect for corrosion, water intrusion, or backed-out pins; a green/white powder on the terminals is the giveaway.
- Probe the sensor connector for 5V reference on the signal wire with key-on engine-off and sensor unplugged — if 5V is present, the wiring back to the PCM is fine and the sensor or sensor ground is the problem; if 5V is absent, you have a wiring break or PCM-side fault.
- Ohm-out the sensor against the OEM thermistor table (typically 9-12 k-ohm at 32 F, 2-3 k-ohm at 70 F, 300-500 ohm at 200 F) — a reading of infinity or zero confirms a dead sensor.
- Swap the sensor ($15-50) and clear. The expensive misdiagnosis: don't chase the wiring back to the PCM on a vehicle where the sensor is bumper-mounted before pulling the sensor and looking at it — physically broken sensor housings from road debris are the #1 cause on Ford F-series and GM trucks, and the wiring is fine.
Vehicle-specific patterns2009-2014 Ford F-150 and 2008-2016 Ford SuperDuty are the highest-volume P0072 vehicles in North American shops — the bumper-mount sensor takes a roc…
- 2009-2014Ford F-150 and 2008-2016 Ford SuperDuty are the highest-volume P0072 vehicles in North American shops — the bumper-mount sensor takes a rock strike or gets crushed against a snow bank and shorts internally, and the mirror-mount variant gets condensation in the connector and reads low.
- 2007-2014GM full-size trucks (Silverado, Sierra, Tahoe, Suburban) set P0072 from corrosion at the bumper-mounted sensor lead where road salt eats the copper and pulls the signal to ground.
- 2008-2015Dodge Ram trucks and 2011-2018 Jeep Grand Cherokee/Dodge Durango set P0072 from grille-mounted sensor damage.
- 2006-2013BMW 3-Series and 5-Series (E90/E60) set P0072 from a wet connector behind the front bumper after the bumper trim has been popped off and replaced incorrectly.
Estimated repair$15 (sensor swap DIY) to $300 (sensor + harness repair + connector).
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