What it means
Voltage on shift fork D position sensor signal line is above the expected window. Wire shorted to B+ or sensor open.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Shift fork D moves an internal transmission selector to engage its assigned gear range, and its position sensor reports that movement to the TCM. P2843 sets when the fork D signal rises above its expected electrical range, so the TCM may interpret the sensor as open or the signal as shorted to battery voltage.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open position sensor
- Connector pins corroded - high contact resistance
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
- Save freeze-frame data and check TCM live data for fork D position and signal status to establish whether the high reading is continuous or intermittent.
- Inspect the fork D sensor connector and harness for corrosion, a backed-out terminal, broken wire, or insulation damage that could let the signal contact battery voltage.
- Check the sensor supply, ground, and signal wiring against the manufacturer's specification, including whether the signal remains high with the sensor disconnected as service information directs.
- With power isolated as directed by the service procedure, test the fork D signal wire for a short to B+ and check connector continuity.
- If the wiring tests pass, test the fork D sensor for an open circuit and replace it if it fails the manufacturer's specification.
Common fixes
- Clean and secure corroded or loose fork D connector terminals.
- Repair a fork D signal wire shorted to B+ or an open in the harness.
- Replace an open fork D position sensor.
Can I keep driving?
Do not continue driving if shifts are missing, slipping, or the transmission enters limp mode; the TCM may not know whether fork D is engaged. If it still shifts normally, keep any trip short and avoid demanding acceleration until diagnosed.
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.