BMW P0112: Intake Air Temperature Sensor 1 Circuit Low Input — Diagnosis and Repair

P0112 means Intake Air Temperature Sensor 1 Circuit Low Input. The DME records it when signal voltage is low and temperature reads implausibly hot; diagnosis must separate an electrical signal fault from a real system fault. Use OBDThink to preserve the recording module and freeze frame for P0112, then test intake-air temperature sensor 1, often integrated in the MAF without guessing or swapping parts. What Does P0112 Mean? This standardized powertrain DTC concerns intake-air temperature sensor 1, often integrated in the MAF. On BMW vehicles the exact test plan and component layout vary by engine, chassis and DME software, so verify the VIN in BMW service information. The decisive clue is not the code alone: signal voltage is low and temperature reads implausibly hot. Compare commanded behavior with the measured signal before condemning a component. Code: P0112 Definition: Intake Air Temperature Sensor 1 Circuit Low Input Module: DME (gasoline) or DDE where applicable Key evidence: signal voltage is low and temperature reads implausibly hot Typical causes: signal short to ground, internally shorted thermistor, chafed harness, connector moisture, or reference-circuit fault Severity: diagnose promptly Note: confirm engine and wiring variant by VIN First preserve the freeze frame. If signal voltage is low and temperature reads implausibly hot, inspect intake-air temperature sensor 1, often integrated in the MAF and its supporting system in the same operating condition. Symptoms • Intake Air Temperature Sensor 1 Circuit Low Input commonly appears with hesitation after throttle changes, incorrect load calculation, mixture correction and uneven response. • The freeze frame may show the fault while signal voltage is low and temperature reads implausibly hot, which is more useful than the warning lamp alone. • Target and actual values separate a persistent defect from an intermittent connector or harness interruption. • A companion fault from the same module may identify whether intake-air temperature sensor 1, often integrated in the MAF is the cause or a consequence. Possible Causes Start with accessible circuit and connection checks, then prove the sensor or actuator, and leave expensive mechanical work until last. • Low cost: inspect the connector, terminal tension, contamination and the harness around intake-air temperature sensor 1, often integrated in the MAF. • Low cost: check hoses, ducts, grounds, fuses and supply paths that directly affect intake-air temperature sensor 1, often integrated in the MAF. • Medium cost: test the named sensor or actuator dynamically; the defining evidence is that signal voltage is low and temperature reads implausibly hot. • Medium cost: correct the system condition rather than masking it; likely branches include signal short to ground, internally shorted thermistor, chafed harness, connector moisture, or reference-circuit fault. • High cost: only after circuit and mechanical evidence, consider control-unit repair or major mechanical work using VIN-specific BMW service data. Diagnosis Steps with OBDThink OBDThink is an independent BMW coding and diagnostic mobile app and is not affiliated with BMW AG. Available live data and freeze frame detail depend on the vehicle, adapter and module. • 1. Scan every control unit with OBDThink; save P0112, the recording DME, status, frequency and freeze frame before clearing anything. • 2. Reproduce the recorded operating condition safely and graph target versus actual values. Compare MAF or intake-temperature data with engine speed, ambient temperature and MAP; inspect the intake tract and sensor circuit. • 3. With ignition safely isolated where required, inspect and electrically test intake-air temperature sensor 1, often integrated in the MAF; load-test power and ground rather than relying on continuity alone. • 4. Separate circuit from mechanism: manipulate the harness while monitoring data, then perform the relevant smoke, vacuum, pressure, airflow or waveform test. • 5. Confirm the repair by clearing the code, completing a cold start and controlled drive cycle, and rescanning all related modules. IF signal voltage is low and temperature reads implausibly hot AND wiring/load test fails -> repair the circuit ELSE IF command is correct but mechanism does not respond -> test intake-air temperature sensor 1, often integrated in the MAF ELSE compare companion faults and BMW VIN-specific test plan THEN clear, drive, and rescan The fastest distinction is to watch the relevant command and actual value while testing intake-air temperature sensor 1, often integrated in the MAF; a fixed signal and a responding mechanism point in different directions. Repair • Low cost: clean and secure the correct connector, repair chafed wiring, restore a fuse/ground, or replace a split hose only when testing proves it. • Medium cost: replace the confirmed sensor, valve, relay or solenoid and perform any BMW service-data adaptation that genuinely applies. • Medium cost: repair the verified airflow, vacuum, exhaust or fuel-delivery defect that caused the implausible reading. • High cost: repair the pump, turbocharger, timing hardware, cylinder-head passage or DME only after VIN-specific testing rules out cheaper causes. After repair, verify that signal voltage is low and temperature reads implausibly hot no longer occurs, readiness can complete, and P0112 does not return as pending or confirmed. Can You Drive with P0112? Short gentle driving may be possible, but stop if the engine stalls or mixture control becomes severe. Treat P0112 as measured evidence, not a parts order. A saved freeze frame, a target/actual comparison and a load-tested circuit usually reveal the least expensive correct repair.