Technical Description of OBD-II Trouble Code
The PRNDL input is experiencing a malfunction in the “B” circuit of the Transmission Range Sensor.
What does that mean?
This code is a generic powertrain code that applies to all makes and models from 1996 onwards. However, the specific troubleshooting steps will vary depending on the vehicle.
The P2800 diagnostic trouble code (DTC) refers to a switch on the transmission, either external or internal, that signals the Powertrain Control Module (PCM) or the Transmission Control Module (TCM) about the gear shift position (P, R, N, and D). The Transmission Range Sensor (TRS) may also control the backup lights if it is an external component.
This code indicates that the computer has detected a failure in the “B” TRS sensor. The sensor is either sending an incorrect signal or no signal at all to the computer, which affects the identification of the gear position. The computer receives signals from both the vehicle speed sensor and the TRS.
When contradictory signals are received by the computer while the vehicle is in motion, such as the TRS signal indicating that the vehicle is in park but the speed sensor indicating movement, the code P2800 is triggered.
As the vehicle ages and accumulates mileage, external TRS failure is common. The external TRS is exposed to weather and elements, which can cause corrosion over time. The good news is that this is not an expensive repair and can be easily replaced even with minimal automotive repair experience.
Example of an external Transmission Range Sensor (TRS):
TRS image from Dorman
Newer models with the TRS located in the valve body present a different challenge. The range sensor is separate from the neutral safety switch and reverse backup light switch. Although its purpose remains the same, replacing it has become more difficult and expensive. To determine which type is used in your vehicle, you can look up the part on your local auto parts website. If it is not listed, then it is an internal TRS.
Symptoms
The symptoms of a P2800 DTC may include:
Potential Causes
The potential causes for this DTC may include:
Diagnostic Steps & Possible Solutions
Replacing an internal TRS requires using a Tech II for diagnosis, followed by draining the transmission and removing the pan. The sensor is located at the bottom of the valve body, which is responsible for all the functions of the transmission. The sensor is constantly submerged in hydraulic fluid, which can cause issues with the casing. Often, hydraulic flow is restricted or O-ring sealing has initiated the problem.
In any case, this is a complex process that is best left to a transmission specialist.
Replacing external transmission range sensors:
Additional Note: The external TR sensor found on some Fords may be referred to as an MLPS or manual lever position sensor.
Related Transmission Range Sensor codes: P2801, P2802, P2803, and P2804.
