A P0112 – Intake Air Temperature (IAT) Sensor Circuit Low Input fault on the 2018 MG ZS indicates that the Engine Control Module (ECM) has detected an intake air temperature sensor signal voltage that is lower than the manufacturer’s calibrated operating range.

The IAT sensor is a thermistor that measures the temperature of the incoming air, enabling the ECM to adjust fuel injection, ignition timing, engine load calculations, and emissions control.

A low input voltage is typically interpreted by the ECM as an unrealistically high intake air temperature, causing it to alter fuel delivery and ignition strategies.

When this condition is detected, the ECM stores Diagnostic Trouble Code P0112 and illuminates the Check Engine Light. Common causes include a short to ground, damaged wiring, a faulty IAT sensor, connector corrosion, or an internal ECM fault.

Symptoms

• Check Engine Light illuminated
• Diagnostic Trouble Code (DTC) P0112 stored
• Reduced engine performance
• Rough or unstable idle
• Engine hesitation during acceleration
• Poor throttle response
• Increased fuel consumption
• Hard starting
• Engine stalling
• Additional intake air or fuel system Diagnostic Trouble Codes may also be present

Possible Causes

The fault may be caused by a defective Intake Air Temperature (IAT) sensor, a short circuit to ground in the IAT signal wire, damaged wiring harnesses, loose or corroded electrical connectors, poor ground connections, water intrusion into the connector, damaged insulation causing low signal voltage, a faulty integrated MAF/IAT sensor assembly (where equipped), Engine Control Module (ECM) faults, or CAN Bus communication issues affecting engine management. Electrical circuit faults and short-to-ground conditions are among the most common causes of DTC P0112.

Diagnosis

Diagnosis begins by connecting a professional diagnostic scan tool to retrieve DTC P0112 together with any related Mass Air Flow (MAF), Manifold Absolute Pressure (MAP), fuel trim, or throttle position Diagnostic Trouble Codes. Freeze-frame data and live data should be analysed to monitor intake air temperature readings, engine coolant temperature, intake manifold pressure, engine load, fuel trim values, battery voltage, and engine speed. An intake air temperature reading that is significantly higher than ambient temperature immediately after a cold start often indicates an electrical fault within the IAT sensor circuit rather than an actual engine operating condition.

A P0112 fault is not always caused by a failed Intake Air Temperature sensor. Technicians typically inspect the sensor connector, wiring harness, and surrounding components for physical damage, corrosion, loose terminals, or evidence of a short to ground before replacing the sensor. The IAT sensor should be tested for correct resistance relative to ambient temperature, while the ECM reference voltage, signal circuit, ground circuit, battery voltage, and related intake sensors should also be verified. Electrical continuity testing, voltage drop testing, and connector pin inspection are commonly performed to identify intermittent wiring faults that may produce a low input signal.

If the Intake Air Temperature sensor and associated electrical circuits operate within specification, further diagnosis should include evaluation of the Engine Control Module, intake air system, sensor reference voltage circuits, and the CAN Bus communication network. Access to OEM wiring diagrams, connector pinouts, IAT circuit descriptions, live data specifications, component locations, sensor resistance charts, and manufacturer diagnostic flowcharts is essential for accurate fault isolation. Following the OEM troubleshooting workflow helps identify the root cause efficiently while avoiding unnecessary replacement of sensors, wiring harnesses, or electronic control modules.

Recommended Resources

OEM Service and Repair Manual

The OEM Service and Repair Manual is the most reliable resource for diagnosing and repairing a P0112 Intake Air Temperature Sensor Circuit Low Input fault. It typically includes:

• Diagnostic procedures specific to DTC P0112
• Engine management wiring diagrams and circuit descriptions
• Intake Air Temperature (IAT) sensor testing procedures
• IAT sensor resistance and voltage specifications
• 5-volt reference, ground, and signal circuit diagnostics
• Live data interpretation procedures
• Intake air system inspection procedures
• Connector pinout information
• Component locations and removal procedures
• OEM troubleshooting workflows
• Repair specifications and electrical testing procedures

To order the correct OEM Service and Repair Manual for your 2018 MG ZS, submit your request using the form below and our team will provide the ordering details.