MG ZS (ZS11) P0335 Crankshaft Position Sensor Circuit Fault

Diagnostic Trouble Code (DTC) P0335 indicates that the Engine Control Module (ECM) has detected a fault in the Crankshaft Position Sensor (CKP) circuit. The CKP sensor monitors the crankshaft’s rotational speed and position, providing the ECM with critical information for ignition timing, fuel injection timing, and engine synchronization. If the ECM does not receive a valid crankshaft position signal, receives an intermittent signal, or detects an electrical fault in the CKP circuit, it stores DTC P0335 and illuminates the Check Engine Light. In severe cases, the engine may crank but fail to start because the ECM cannot accurately synchronize ignition and fuel injection.

Symptoms

• Check Engine Light illuminated
• Engine cranks but does not start
• Engine stalls unexpectedly
• Hard starting or extended cranking
• Rough idle
• Poor acceleration
• Engine hesitation
• Intermittent loss of power
• Tachometer may not register engine speed during cranking
• Engine-related Diagnostic Trouble Codes (DTCs) stored

Possible Causes

• Faulty Crankshaft Position Sensor (CKP)
• Open or short circuit in the CKP sensor wiring
• Loose or corroded CKP sensor connector
• Damaged wiring harness
• Faulty reluctor wheel (trigger wheel)
• Incorrect sensor air gap
• Poor sensor ground connection
• Faulty 5-volt reference or power supply circuit (where applicable)
• Timing chain or timing component problems affecting crankshaft synchronization
• Water or oil contamination at the sensor connector
• Faulty Engine Control Module (ECM) (rare)

Diagnosis

Diagnosis begins by retrieving all stored Diagnostic Trouble Codes (DTCs) and freeze-frame data using an OEM-compatible diagnostic scan tool. Live data should be monitored while cranking the engine to verify that the ECM is receiving an engine speed (RPM) signal. If engine speed remains at 0 RPM during cranking, the CKP sensor or its circuit should be suspected. Related DTCs such as P0336, P0340, P0016, or synchronization faults should also be diagnosed, as they may indicate timing or camshaft position sensor issues.

The Crankshaft Position Sensor, reluctor wheel, wiring harness, electrical connectors, and mounting area should be inspected for damage, corrosion, loose terminals, oil contamination, or physical contact with rotating components. Electrical testing should include verifying the sensor power supply (where applicable), ground integrity, signal circuit continuity, and sensor output using a digital multimeter or oscilloscope according to OEM specifications. The reluctor wheel should also be inspected for damaged, missing, or contaminated teeth and correct alignment. If the sensor and wiring test within specification but the fault persists, the technician should inspect engine mechanical timing and test the ECM input circuit before replacing the control module.

For vehicles operating in New Zealand, following OEM diagnostic procedures helps accurately distinguish between a faulty Crankshaft Position Sensor, damaged reluctor wheel, wiring defect, timing problem, poor electrical connection, or ECM fault before replacing expensive engine management components.

Accurately diagnosing this fault often requires manufacturer testing procedures, wiring diagrams, ECU pinouts, connector views, crankshaft position sensor circuit schematics, reluctor wheel specifications, engine timing procedures, live data reference values, oscilloscope waveform analysis, and ECM diagnostic flowcharts. Access to the factory service manual significantly reduces diagnostic time and helps prevent unnecessary parts replacement.

Applicable Years

2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024

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