P2264 on the 6.7L Cummins is a water in fuel (WIF) sensor circuit range or performance fault. The 6.7L runs a water-in-fuel sensor in the fuel filter and water separator housing so the ECM can warn you before water reaches the CP3 or CP4 high-pressure pump and the injectors. P2264 sets when that sensor signal is present but does not behave rationally, so the ECM cannot trust whether water is actually being detected.
This code matters more than it may seem. Water is the single most damaging contaminant in a common-rail diesel fuel system, and the WIF sensor is your early warning. When P2264 sets, you lose confidence in that warning, so you should confirm whether there is real water in the fuel and, separately, whether the sensor and its wiring are healthy. It is usually an inexpensive repair, but ignoring it risks a very expensive pump and injector failure.
What P2264 means
The water-in-fuel sensor uses the difference in electrical conductivity between diesel and water to detect accumulated water in the separator. P2264 is a rationality code: the signal exists but is out of the expected range, drifts, or does not respond as the ECM expects. It points to the sensor, its connector, the wiring, or genuinely contaminated or aerated fuel rather than a simple hard short or open.
Common causes
- Actual water accumulation the separator has not been drained
- Failed or drifting water-in-fuel sensor
- Corroded or loose sensor connector in the filter housing
- High-resistance or chafed wiring to the sensor
- Contaminated fuel or heavy debris coating the sensor tip
Symptoms
- Check engine light with P2264 stored
- Water-in-fuel warning light on or behaving erratically
- Little drivability change in many cases
- Rough running or hard starting if water is truly present
- Companion fuel system or rail pressure codes
How to diagnose it
Start by draining the fuel filter and water separator and noting how much water comes out, since real water contamination is the first thing to rule out. Inspect the WIF sensor connector for corrosion, moisture, and a secure fit, and back-probe to confirm a clean reference and ground. Watch the sensor status with a scan tool and compare it to what you drained. Check the wiring for high resistance or chafing near the filter housing. Measure the sensor if a specification is available, and confirm the ground is clean.
How to fix it
Drain the separator and, if water was present, replace the fuel filters and confirm the fuel source is clean. Clean or repair a corroded connector and fix any high-resistance wiring, then confirm a clean ground. If the wiring is good but the sensor reads implausibly, replace the water-in-fuel sensor. After the repair, clear the code, verify the sensor status is stable, and road test. For water separators, filters, and water-in-fuel sensors for your 6.7L Cummins, contact sales@coredieselparts.com.
Frequently asked questions
Is P2264 dangerous to ignore?
It can be. The sensor protects your pump and injectors from water. If you cannot trust it, water can reach the fuel system undetected, so confirm the fuel is dry and repair the circuit promptly.
Does P2264 mean there is water in my fuel?
Not necessarily. It means the sensor reading is not rational. Drain the separator to check for real water, then diagnose the sensor and wiring if the fuel is dry.
Can a dirty sensor cause P2264?
Yes. Debris or contamination coating the sensor tip can skew its reading. Clean the sensor and separator, and replace the sensor if it still reads incorrectly.
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