Technical Description of OBD-II Trouble Code
The circuit of the Water in Fuel Sensor is experiencing low voltage
What does that signify?
This is a generic diagnostic trouble code (DTC) that is applicable to many OBD-II vehicles (1996-newer). This includes vehicles from Land Rover (Range Rover), Ford, Hyundai, Jeep, Mahindra, Vauxhall, Dodge, Ram, Mercedes, etc. Although it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
The OBD-II trouble code P2266 is associated with the circuit of the water in fuel sensor, also known as the fuel composition circuit. When the Power Control Module (PCM) detects an excessively low electrical signal within the water in fuel sensor circuit, code P2266 will be set and the check engine light will illuminate. If the vehicle has a warning indicator for water in fuel, that light may also illuminate. To find the location of the sensor for your specific year/make/model configuration, refer to a vehicle-specific resource.
The purpose of the water in fuel sensor is to monitor the fuel passing through it to ensure that the percentage of ethanol, water, and other contaminants does not exceed a certain level. Additionally, the water in fuel sensor measures the fuel temperature and converts it into a voltage pulse width, which is monitored by the PCM. The PCM uses these readings to adjust the engine timing for optimal performance and fuel economy.
A typical water in fuel sensor:
What is the severity of this DTC?
The severity of this code can vary greatly, ranging from just an illuminated check engine light or water in fuel light on a vehicle that starts and runs, to a vehicle that may stall, misfire, or not start at all. If this issue is not addressed promptly, it can cause damage to the fuel system and internal engine components.
What are some of the symptoms of the code?
Symptoms of a P2266 trouble code may include:
What are some of the common causes of the code?
Causes for this P2266 code may include:
What are some P2266 troubleshooting steps?
The first step in the troubleshooting process for any malfunction is to research the Technical Service Bulletins (TSB’s) for the specific vehicle by year, model, and power plant. This can save a lot of time by providing guidance in the right direction.
The second step is to check the vehicle records to see when the fuel filter was last replaced and visually inspect its condition. The most common causes for this code are a defective fuel filter or contaminated fuel. A visual inspection of the fuel can be done using a glass jar. After taking a sample and allowing it to settle, the water and fuel will separate within minutes. The presence of water in the fuel indicates contaminated fuel, a defective fuel filter, or both. Next, locate all the components within the water in fuel circuit and perform a thorough visual inspection of the associated wiring for any obvious defects such as scraping, rubbing, bare wires, or burn spots. Check the connectors for security, corrosion, and damaged pins. The sensor is usually mounted on the top of the fuel tank in most vehicles.
Advanced Steps
The advanced steps are highly specific to the vehicle and require advanced equipment for accurate performance. These procedures involve using a digital multimeter and specific technical references for the vehicle. If available, an oscilloscope is the ideal tool to use in this situation. The oscilloscope provides an accurate illustration of the signal pulses and frequency levels, which are proportional to the fuel contamination level. The typical frequency range is from 50 to 150 hertz, with 50 hertz representing clean fuel and 150 hertz representing a high level of contamination. Voltage requirements and signal pulses vary based on the specific year and model of the vehicle.
Voltage Checks
The water in fuel sensor typically receives a voltage reference of approximately 5 volts from the PCM. If this process identifies the absence of a power source or ground, continuity testing may be required to check the integrity of the wiring, connectors, and other components. Continuity tests should always be performed with the power removed from the circuit, and the normal readings for wiring and connections should be 0 ohms of resistance. Resistance or no continuity indicates faulty wiring that is either open or shorted and must be repaired or replaced.
What are some common repairs for this code?
Common mistakes may include:
Replacing the PCM or water in fuel sensor when the cause of the problem is damaged wiring or contaminated fuel.
We always recommend seeking professional service to address this issue. However, if that is not possible, we offer the option to permanently delete this specific DTC. All other codes will continue to function. If you are interested in this option, please upload your ECU file to our portal.
