GWM Water Trap Sensor 2.0

Description

OBD Fault Codes Related to the GWM Water Trap Sensor
The most common OBD-II fault codes associated with a failing or faulty water trap sensor on GWM diesel vehicles are P226400, P226600, P226700, and P226900.

P226400 — Water in Fuel Sensor: Open Circuit
This code is logged when the ECU detects an open circuit in the sensor signal voltage, identified through chip self-diagnosis. It indicates a break in the sensor wiring, a damaged connector, or a failed sensor rather than actual water in the fuel. The engine warning light will illuminate, but the fault is electrical in nature and does not necessarily mean water contamination is present.

P226600 — Water in Fuel Sensor: Signal Short Circuit to Ground
This code is triggered when the sensor signal voltage is short-circuited to ground, detected through chip self-diagnosis. It points to a wiring fault or internal sensor failure causing the signal line to ground out. As with P226400, this is a circuit fault rather than a water detection event, and the sensor or its wiring harness should be inspected and tested before replacement.

P226700 — Water in Fuel Sensor: Signal Short Circuit to Power Supply
This code is stored when the sensor signal voltage is short-circuited to the power supply, also identified through chip self-diagnosis. It is caused by a wiring fault or a faulty sensor allowing the signal line to connect to a voltage source. Inspect the sensor connector and wiring harness for chafing, pinching, or corrosion before replacing the sensor.

P226900 — Water in Fuel Detected
This code is the most serious of the four. It is logged when the ignition is on, coolant temperature is above -40°C, and battery voltage exceeds 10V, and the sensor outputs a high-level signal indicating water has been detected in the fuel. When P226900 is active, the service indicator illuminates and the ECU activates limp-in mode with torque limitation to protect the engine. This code typically means the water separator bowl was not drained in time and water has accumulated to a critical level in the fuel filter housing. Drain the water separator bowl immediately, clear the fault code, and confirm it does not return before resuming normal operation. Ignoring this code risks severe damage to fuel injectors, the high-pressure pump, and internal fuel system components.

In all four cases, always clear the fault codes after repair or drainage and confirm the fault does not return before returning the vehicle to normal operation. Regular draining of the water separator bowl is essential preventative maintenance on all GWM diesel platforms.

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