What P0111 means
P means powertrain (engine and transmission). The 0 marks a generic code defined by SAE, so the same number means the same thing across makes. The third character, 1, places it in the fuel and air metering subsystem; the last two digits identify the specific fault.
The IAT sensor is a thermistor in the intake tract (sometimes built into the MAF housing) that reports the temperature of incoming air. The engine computer uses it to correct air density for fuelling and, on many engines, to adjust ignition timing.
Bank 1 is the side of the engine that contains cylinder 1. Inline engines have only bank 1, so a bank 2 code on an inline engine usually indicates a manufacturer-specific use.
What “Range/Performance” means here
"Range/Performance" means the circuit is electrically intact — the signal sits inside its normal window — but the value does not make sense for the operating conditions. The module cross-checks it against what other inputs predict (a rationality test). That usually points at the intake air temperature (IAT) sensor itself or the system it measures, rather than at the wiring.
What you may notice
Symptoms depend on the vehicle and on how the module responds to the fault. Any of these can accompany P0111:
- Often no noticeable symptom
- Slight hesitation or rough running on cold starts
- Small changes in fuel economy
Where to start diagnosing P0111
- On a cold engine that has sat overnight, IAT and coolant temperature should read within a few degrees of each other and of the outside air.
- Inspect the connector and wiring, especially if the sensor is part of the MAF assembly.
- Check for a heat source affecting the reading, such as a disconnected intake duct drawing hot under-bonnet air.
Clear the code only after recording freeze frame data: it shows the engine speed, load and temperature at the moment the fault set, which is often the best clue to reproducing it.
Live data to watch
These standard OBD2 values relate to P0111. Support varies by vehicle; a value your car does not report will simply be missing.
| Value | What to look for |
|---|---|
| Intake air temperature (PID 0x0F) | Should be near ambient on a cold start and climb modestly when idling in traffic. |
| Engine coolant temperature (PID 0x05) | Cold-start comparison point. |
Related codes
Codes from the same intake air temperature (IAT) sensor family. If several are stored together, the shared part — wiring, a common reference voltage, or the component itself — is the place to start.
Further reading
Frequently Asked Questions
What does P0111 mean?
P0111 is the generic SAE J2012 code for "Intake Air Temperature Sensor 1 Circuit Range/Performance". In plain terms, it means the engine computer has detected a "range/performance" fault on the intake air temperature (IAT) sensor.
Can I keep driving with P0111?
Usually drivable; the engine computer substitutes a default value. Diagnose it to keep fuelling and timing corrections accurate.
What should I check first for P0111?
On a cold engine that has sat overnight, IAT and coolant temperature should read within a few degrees of each other and of the outside air.
Definition source: SAE J2012 / ISO 15031-6 generic DTC definitions. This is the generic meaning that applies across makes; a manufacturer can define a code more narrowly or add its own sub-codes, so confirm against the service information for your vehicle before replacing parts. Written by the OBDAssistant engineering team — see our editorial policy.