What it means
The range sensor B signal drops out intermittently. Loose connector or vibration-sensitive solder joint.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Range sensor B sends the transmission control unit a signal for selector position. P2804 sets when that signal drops out or changes unpredictably at intervals, often because a connector or wire loses contact with vibration or movement.
Common causes
Most likely first.
- Sensor connector not seated
- Harness chafing intermittently grounds the wire
- Connector with intermittent contact under vibration
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Read freeze-frame and fault history, then monitor live B-channel data to see whether the signal drops out as the selector is moved.
- Inspect the range sensor B connector for incomplete seating, loose terminals, corrosion, or moisture.
- Follow the B-channel harness and look for chafing, pinching, or damage near moving parts and hot surfaces.
- With live data or a meter, gently move the connector and harness to check for a repeatable signal interruption without disturbing other circuits.
- Check B-channel continuity and terminal fit using the manufacturer’s wiring information and specification.
Common fixes
- Reseat and secure the range sensor B connector.
- Clean or replace terminals with intermittent contact.
- Repair chafed or damaged B-channel wiring and secure the harness away from rubbing points.
- Replace range sensor B if its output intermittently fails with stable wiring and connections.
Can I keep driving?
Driving may become unpredictable if the B-channel drops out, causing harsh or missing shifts or limp mode. Avoid longer trips and stop if the range indication changes unexpectedly or the transmission slips.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.