P238B code meaning
Water in Fuel Sensor B Circuit Range/Performance
What P238B means
P238B means water-in-fuel sensor B delivers a signal that is electrically valid but implausible, for instance a value stuck between the clear dry and wet states, or a self-test answer that arrives at the wrong moment. No manufacturer documents P238B publicly. On 2022 Ram heavy-duty diesels sensor B is fitted to the frame-mounted filter, exposed to road spray (Stellantis case S2214000004). The probe judges conductivity, so a film of dirt, biodiesel deposits or a partly corroded electrode can shift its reading. For the sensor A codes on 2025–26 Ram trucks Stellantis advises draining both filter stages and wiping the probe before replacing anything, a sensible first step here as well. Unlike P238F it does not confirm water.
P238B at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P238B
- Water-in-fuel warning without water being found
- Warning that persists after draining
Common causes of P238B
- Most likelyDirt film or deposits on the sensor electrodes
- PossibleResidual water or emulsion around the probe after incomplete draining
- PossibleCorroded or aged sensor
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Water in fuel sensor b
What each part of P238B means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 3 | Area: ignition system or misfire. |
| 8B | The exact fault in that area. |
What to do next
- Note P238B and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P238B
What does P238B mean?
P238B means "Water in Fuel Sensor B Circuit Range/Performance". P238B means water-in-fuel sensor B delivers a signal that is electrically valid but implausible, for instance a value stuck between the clear dry and wet states, or a self-test answer that arrives at the wrong moment. It is a generic code, so it means the same on every make.
Is it safe to drive with P238B?
P238B does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P238B fail an emissions test?
P238B is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P238B to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P238B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.