P2843 means the transmission control module has detected a voltage above the expected range on the electrical circuit for the shift fork "D" position sensor. This sensor tells the module where the shift fork is located as it engages different gears; a "high" reading usually points to an open circuit, short to voltage, or sensor fault rather than a normal position signal.
The sensor itself can fail internally, causing an open or shorted signal line so the control module sees a high voltage. This is the most common root cause for a circuit-high code.
An open in the signal or ground path, a short to a higher-voltage wire, corrosion, or a pushed/p damaged pin can raise the circuit voltage seen by the module.
If the position sensor is integrated into the mechatronic unit or shift actuator, internal damage or contamination can produce an out-of-range high signal.
Less commonly, a bent, worn, or binding shift fork may hold the sensor at an extreme position and contribute to an abnormal circuit reading.
A rare cause is an internal TCM/PCM problem misreading a normal sensor voltage; it should only be considered after the sensor circuit and wiring are proven good.
It is not recommended. The transmission may enter limp mode, limit available gears, or shift harshly, and continued driving can increase internal wear or damage.
Most often it is the position sensor, its wiring, or the mechatronic unit. Actual mechanical damage to the shift fork is less common, but it should be inspected if electrical tests are normal.
Usually no. PCM or TCM failure is a rare cause of this code. The problem is typically in the sensor circuit inside the transmission or the related wiring, so replacing the control module without verifying those is generally unnecessary.
"High" means the voltage on the sensor signal circuit is above the expected range. This commonly happens with an open circuit, a short to a higher voltage source, or an internally failed sensor.