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, variable valve timing, and engine synchronization. If the ECM detects a missing, intermittent, or implausible crankshaft position signal, or an electrical fault within the CKP sensor circuit, it stores DTC P0335 and illuminates the Check Engine Light. Because the ECM relies on this signal to control ignition and fuel injection, a CKP circuit fault can result in severe driveability problems or a complete no-start condition.

Symptoms

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

Possible Causes

• Faulty Crankshaft Position Sensor (CKP)
• Open circuit in the CKP sensor wiring
• Short circuit in the CKP sensor circuit
• Loose or corroded CKP sensor connector
• Damaged wiring harness
• Faulty crankshaft reluctor (trigger) wheel
• Excessive sensor air gap
• Poor sensor ground connection
• Oil or water contamination at the sensor connector
• Engine timing component damage affecting crankshaft synchronization
• 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 whether the ECM is receiving an engine speed (RPM) signal. If engine speed remains at 0 RPM while the engine is cranking, the CKP sensor or its electrical circuit is the primary suspect. Related DTCs such as P0336, P0340, P0016, or other synchronization faults should also be diagnosed, as they may indicate timing or camshaft position sensor problems.

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 damage. 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, bent, or contaminated teeth and proper alignment. If the sensor and wiring test within specification but the fault remains, engine mechanical timing should be checked before testing the ECM input circuit and 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, poor electrical connection, engine timing problem, 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 inspection 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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