P238AWater in Fuel Sensor B Circuit
- Generic OBD-II code · Powertrain
- How the car detects it
- P238A is the general circuit code for water-in-fuel sensor B, used where a diesel has two water-detecting points, for example a frame-mounted primary filter and a second separator. Stellantis case file S2214000004 for 2022 Ram 2500 to 5500 trucks shows that on these vehicles the B sensor is part of the fuel filter mounted on the frame; P238A itself is not named there. No manufacturer documents P238A publicly. The sensor works like sensor A: two electrodes in the water sump read the conductivity. GM's 2018 diesel tables describe a self-test for sensor A in which a healthy probe briefly reports water right after power-up; a missing pulse counts as a circuit fault. While the code is stored, real water in the filter may go unnoticed, so drain the separator regularly.
- What you may notice
- Water-in-fuel lamp or message on
- No warning for real water in the chassis filter
- Likely causes
- LikelyWater or corrosion in the sensor B connector at the chassis filter
- PossibleDamaged harness along the frame rail
- PossibleWater-in-fuel sensor B failed
- Repair
- Easy · Often possible to do yourself.Typical cost: €0 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.