Diagnostic article Generic OBD-II
P2801: Range sensor B frequency must be checked separately from its position duty cycle
Understand Ford P2801 PWM frequency monitoring and the difference between channel B timing and A/B correlation.
Read before applying this article
Documented application
Ford 2024–2025 gasoline OBD operation summary, July 16 2024 revision; only the cited monitor and transmission architectures. No individual vehicle fitment or universal calibration is inferred.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P2801 is assigned to transmission range sensor B's out-of-range frequency in Ford's cited PWM tables. A duty cycle that decodes to a plausible selector position does not establish that the signal's repetition rate meets the controller's requirement.
Choose the architecture's frequency criterion
Ford's general range-sensor section gives a 100–175 Hz example window. The architecture tables instead describe a nominal 125 Hz with a 25 Hz allowance. These are documented variants; the exact transmission and calibration must determine the applicable limit rather than averaging or combining them.
The same tables distinguish duty-cycle extremes from frequency faults and separately evaluate whether A and B duty cycles add to the expected total. A correlation result and P2801's B-frequency classification therefore answer different questions.
Preserve both channels without confusing their roles
A useful capture records B frequency, B duty cycle, the A channel and the selected range together. A decoded gear value alone may hide a timing fault. If B is currently normal, retain the circumstances of the stored event rather than treating the latest value as a reproduction.
The detailed representation is P2800_38. The source does not provide a universal B-sensor location or connector procedure. Verification needs the matched range-sensor design and its electrical information before the frequency result can justify any component replacement.
Source and applicability
Ford 2024–2025 gasoline OBD operation summary, July 16 2024 revision; only the cited monitor and transmission architectures. No individual vehicle fitment or universal calibration is inferred. Ford PDF, page 147. Ford PDF, page 148. Ford PDF, page 155. Ford PDF, page 157.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Transmission Range Sensor B Circuit Range/Performance
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT