A P0113 – Intake Air Temperature (IAT) Sensor Circuit High 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 higher than the manufacturer’s specified operating range.

The IAT sensor is a negative temperature coefficient (NTC) thermistor that measures the temperature of the incoming air, allowing the ECM to calculate air density and optimize fuel injection, ignition timing, engine load, and emissions control. A high input voltage is typically interpreted as an unrealistically low intake air temperature, often around -40°C (-40°F), causing the ECM to enrich the air-fuel mixture and adjust engine operating parameters.

When this condition is detected, the ECM stores Diagnostic Trouble Code P0113 and illuminates the Check Engine Light. Common causes include an open circuit, disconnected sensor, damaged wiring, poor electrical connections, or a faulty IAT sensor.

Symptoms

• Check Engine Light illuminated
• Diagnostic Trouble Code (DTC) P0113 stored
• Hard starting, particularly when the engine is warm
• Rough or unstable idle
• Engine hesitation during acceleration
• Reduced engine performance
• Increased fuel consumption
• Black exhaust smoke caused by an overly rich air-fuel mixture
• Poor throttle response
• 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, an open circuit in the IAT signal or ground wire, disconnected sensor connector, loose or corroded electrical terminals, damaged wiring harnesses, poor connector contact, excessive circuit resistance, a faulty integrated MAF/IAT sensor assembly (where equipped), Engine Control Module (ECM) faults, or CAN Bus communication issues affecting engine management. Open circuits and disconnected sensors are among the most common causes of DTC P0113.

Diagnosis

Diagnosis begins by connecting a professional diagnostic scan tool to retrieve DTC P0113 together with any related Mass Air Flow (MAF), Manifold Absolute Pressure (MAP), throttle position, engine coolant temperature, or fuel trim 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, battery voltage, and fuel trim values.

If the intake air temperature immediately displays an implausibly low value (such as -40°C) with the ignition switched on, the technician should suspect an open circuit or disconnected sensor before replacing components.

A P0113 fault is not always caused by a failed Intake Air Temperature sensor. Technicians typically inspect the sensor connector, wiring harness, and surrounding components for loose terminals, corrosion, damaged insulation, broken wires, or connector damage before replacing the sensor.

The IAT sensor should be tested for correct resistance relative to ambient temperature, while the ECM 5-volt reference, signal circuit, ground circuit, battery voltage, and related intake sensors should also be verified. Electrical continuity testing, resistance testing, and connector pin inspection are commonly performed to identify intermittent open circuits or excessive circuit resistance affecting the IAT 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, connectors, 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 P0113 Intake Air Temperature Sensor Circuit High Input fault. It typically includes:

• Diagnostic procedures specific to DTC P0113
• Engine management wiring diagrams and circuit descriptions
• Intake Air Temperature (IAT) sensor testing procedures
• IAT sensor resistance and voltage specifications
• 5-volt reference, signal, and ground 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

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