DTC P0112: Intake Air Temperature Sensor Circuit Low Input

In the intricate landscape of automotive diagnostics, diagnostic trouble codes (DTCs) provide valuable insights, pointing mechanics toward potential issues within a vehicle’s systems. Among these, DTC P0112 emerges as a significant indicator of problems related to the Intake Air Temperature (IAT) sensor circuit’s low input. This comprehensive article delves into the causes, symptoms, inspection procedures, and effective solutions for addressing and resolving DTC P0112.

1. Causes of DTC P0112:

DTC P0112 surfaces when the Engine Control Module (ECM) detects a lower-than-expected voltage signal from the Intake Air Temperature (IAT) sensor. The underlying causes can encompass:

– Faulty IAT sensor: A sensor that inaccurately measures the temperature of incoming air can lead to a low voltage signal.

– Wiring and connector issues: Damaged, corroded, or loose wiring and connectors within the IAT sensor circuit can disrupt signal transmission.

– Air intake restrictions: Blockages in the air intake system can lead to lower temperature readings.

– ECM communication problems: An ECM malfunction or communication breakdown can result in misinterpretation of IAT sensor data.

2. Symptoms of DTC P0112:

Recognizing the symptoms associated with DTC P0112 aids mechanics in effectively diagnosing the issue:

– Decreased engine performance: Incorrect temperature data can lead to imbalanced air-fuel mixture and compromised engine power.

– Fuel efficiency fluctuations: Erroneous temperature readings can result in varying fuel economy.

– Rough idling or stalling: Inaccurate temperature measurements can cause the engine to idle roughly or stall.

– Illuminated Check Engine Light (CEL): DTC P0112 triggers the CEL to alert the driver of a potential problem.

3. Inspection of DTC P0112:

Thorough inspection techniques are crucial for accurate diagnosis:

– OBD-II scan: Utilize an OBD-II scanner to retrieve the DTC and accompanying freeze frame data, providing insight into the conditions that activated the code.

– Visual examination: Inspect the IAT sensor, wiring, and connectors for visible signs of damage, contamination, or corrosion.

– IAT sensor testing: Measure the sensor’s output using a multimeter or scan tool and compare it to manufacturer specifications.

– Air intake system inspection: Check for blockages or restrictions in the air intake system that might lead to lower temperature readings.

4. Resolving Causes of DTC P0112:

Addressing DTC P0112 involves specific steps based on the underlying issue:

– IAT sensor replacement: Replace a malfunctioning sensor with a new, high-quality unit that meets manufacturer specifications.

– Air intake system repair: Clear any blockages in the air intake system to ensure accurate temperature measurements.

– Wiring and connector repair: Repair or replace damaged wiring and connectors to restore proper signal transmission.

– ECM diagnosis: If an ECM malfunction is suspected, diagnose and rectify the issue through reprogramming or replacement.

5. Clearing DTC P0112:

After successfully addressing the root cause, clear the DTC from the ECM’s memory using an OBD-II scanner. This step confirms the issue’s resolution and prevents the recurrence of the CEL.


DTC P0112, indicative of an Intake Air Temperature sensor circuit low input, can significantly impact a vehicle’s performance and fuel efficiency. Through a comprehensive understanding of its causes, recognition of its symptoms, meticulous inspection techniques, and effective solutions, mechanics can accurately diagnose and rectify this issue. Maintaining optimal air-fuel mixture and engine performance remains crucial for ensuring a vehicle’s reliability and driving experience.