OBD-II Code
P1112
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)
$40–$280
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
$40 (clean connector, dielectric grease) to $280 (OEM IAT B sensor + pigtail repair on EcoBoost intercooler).
P1112 is a Ford-specific code meaning the IAT sensor B circuit is reading intermittent — voltage at the PCM signal pin is jumping in and out of the legal 0.5-4.5 V scaled range (which corresponds to roughly -40 F at 4.5 V down to 248 F at 0.5 V on a standard NTC thermistor) instead of moving smoothly with airflow.
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 procedureP1112 is a Ford-specific code meaning the IAT sensor B circuit is reading intermittent — voltage at the PCM signal pin is jumping in and out of the l…
P1112 is a Ford-specific code meaning the IAT sensor B circuit is reading intermittent — voltage at the PCM signal pin is jumping in and out of the legal 0.5-4.5 V scaled range (which corresponds to roughly -40 F at 4.5 V down to 248 F at 0.5 V on a standard NTC thermistor) instead of moving smoothly with airflow.
Cheapest-first ladder
- Scan-tool live data — watch IAT B with the key on and tap/wiggle the sensor connector and the harness from the sensor back to the PCM; a value that jumps 30+ degrees on wiggle is harness/connector, a value that reads steady but wrong is the sensor itself.
- Back-probe the signal wire and ohm the sensor — Ford IAT spec is roughly 95-100 kohms at -40 F, 35-40 kohms at 32 F, 2-3 kohms at 176 F, 0.7-1.0 kohm at 248 F; out-of-curve readings condemn the sensor for ~$25.
- Check connector pins for green/white corrosion (especially on intercooler-mounted IAT B sensors on EcoBoost trucks that see road-spray) — DeoxIT and a re-pin often clears the code permanently. Don't replace the PCM or the entire intake manifold harness before reading the keep-alive memory for prior tune flashes — aftermarket tunes (SCT, Livernois, Bully Dog) sometimes rescale the IAT B input for boost-cooler kits and leave the diagnostic threshold wrong, which is a software fix, not a parts fix.
Vehicle-specific patterns2011-2018 Ford F-150 EcoBoost 3.5L / 2.7L commonly throws P1112 from the intercooler-outlet IAT B sensor (the second IAT used to compute charge-air t…
- 2011-2018Ford F-150 EcoBoost 3.5L / 2.7L commonly throws P1112 from the intercooler-outlet IAT B sensor (the second IAT used to compute charge-air temp post-intercooler) — condensation pools in the connector after washing and the sensor reads erratically; this is the single most common P1112 in modern Ford shop work.
- 2015-2020Ford Mustang EcoBoost 2.3L throws P1112 from a known harness routing where the IAT B pigtail crosses the turbo heat shield.
- 2008-2010Ford F-250/F-350 6.4L Powerstroke diesel throws P1112 from EGR-cooler crud blocking the IAT B sensor face, giving artificially slow response — clean the sensor tip before replacing.
- 1997-2003Ford F-150 / Crown Vic 4.6L Triton with the older two-sensor IAT setup will throw P1112 from a brittle connector lock that intermittently loses contact with engine vibration.
Estimated repair$40 (clean connector, dielectric grease) to $280 (OEM IAT B sensor + pigtail repair on EcoBoost intercooler).
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