Powertrain, generic (extended)

P255B PTO Speed Selector Sensor/Switch 2 Range/Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

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.

Likely causes

Sticking selector 2 switch
Upfitter wiring ties selector 1 and 2 together
Number of programmed presets does not match the switch

Symptoms

  • Second preset ignored or wrong speed reached
  • PTO speed control falls back to standby

Repair estimate

DifficultyMediumDIY possible
Parts and labour€20–300
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

pto speed selector 2

Related codes

P255AP255CP255DP255EP254B

References: law.cornell.edu, http:.