P255B code meaning
PTO Speed Selector Sensor/Switch 2 Range/Performance
What P255B means
P255B flags an implausible reading from PTO speed selector 2 although its circuit is electrically intact. Because a second selector normally works together with the first, the check can compare both: requests that cannot coexist, a level that sits between valid positions, or a selection that the configured number of presets does not allow. On Ram chassis cabs from 2012 the Cummins controller can be set to between one and five remote PTO speeds, so a selector reporting a step beyond the programmed count would be a candidate for such a fault. CARB calls this a rationality diagnostic. No manufacturer documents P255B publicly. Suspects are a sticky switch, an upfitter wiring mistake that ties both inputs together, or a configuration that does not match the hardware.
P255B at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P255B
- Second preset ignored or wrong speed reached
- PTO speed control falls back to standby
Common causes of P255B
- Most likelySticking selector 2 switch
- PossibleUpfitter wiring ties selector 1 and 2 together
- Less likelyNumber of programmed presets does not match the switch
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Pto speed selector 2
What each part of P255B means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 5 | Area: vehicle speed, idle control and auxiliary inputs. |
| 5B | The exact fault in that area. |
What to do next
- Note P255B 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 P255B
What does P255B mean?
P255B means "PTO Speed Selector Sensor/Switch 2 Range/Performance". P255B flags an implausible reading from PTO speed selector 2 although its circuit is electrically intact. It is a generic code, so it means the same on every make.
Is it safe to drive with P255B?
P255B does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P255B fail an emissions test?
P255B 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 P255B to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P255B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.