A throttle position sensor (TPS) fault on the 2017 MG ZS indicates that the Engine Control Module (ECM) is receiving an incorrect or inconsistent signal about the position of the electronic throttle valve. This can affect throttle response, engine performance, and idle stability, and may place the vehicle into a reduced power mode. Accurate diagnosis is essential because the sensor is often integrated into the electronic throttle body, and similar symptoms can also be caused by wiring faults, power supply issues, or electronic control module problems.

Symptoms

• Check Engine Light illuminated
• Reduced engine power or limp mode
• Poor throttle response
• Hesitation during acceleration
• Rough or unstable idle
• Engine stalling when coming to a stop
• Inconsistent engine speed
• Poor fuel economy
• Difficulty maintaining a steady speed
• Diagnostic Trouble Codes such as P0121, P0122, P0123 or P2135 may be stored

Possible Causes

The fault may be caused by a defective throttle position sensor, a faulty electronic throttle body, damaged wiring, loose or corroded electrical connectors, poor ground connections, low system voltage, contamination inside the throttle body, Engine Control Module (ECM) faults, or communication problems affecting throttle control.

Diagnosis

Diagnosis usually begins by confirming the stored Diagnostic Trouble Codes and reviewing live scan tool data to compare the throttle position sensor signals with the accelerator pedal position. Freeze-frame data can also help identify the operating conditions under which the fault occurred. Because the 2017 MG ZS uses an electronic throttle control system, technicians will often verify that the throttle plate responds correctly to ECM commands before replacing any components.

In practice, a throttle position sensor fault is not always caused by the sensor itself. Wiring damage, poor connector contact, low reference voltage, ground circuit faults, or communication issues between the ECM and throttle body can produce identical symptoms. Technicians typically verify the 5-volt reference supply, ground integrity, signal voltage, and connector condition before performing continuity and circuit integrity tests.

If the throttle body assembly and associated circuits test correctly, further diagnosis may be required on the Engine Control Module and related control systems. Access to OEM wiring diagrams, connector pinouts, component locations, circuit descriptions, manufacturer test procedures, and OEM troubleshooting workflows is essential for accurate diagnosis. Following the recommended diagnostic process helps identify the root cause efficiently and avoids unnecessary replacement of the throttle body or other expensive components.

Recommended Resources

OEM Service and Repair Manual

The OEM Service and Repair Manual is the most reliable resource for diagnosing and repairing this fault. It typically includes:

• Diagnostic procedures specific to this fault
• Wiring diagrams and circuit descriptions
• Connector pinout information
• Component locations and removal procedures
• OEM troubleshooting workflows
• Repair specifications and testing procedures

To order the correct OEM Service and Repair Manual for your 2017 MG ZS, submit your request using the form below and our team will provide the ordering details.