What it means
Voltage on shift fork D position sensor signal line is below the expected window. Wire shorted to ground or sensor short.
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. The TCM sets P2842 when the fork D signal falls below the expected electrical range, which can make the fork's actual position unreadable.
Common causes
Most likely first.
- Signal wire shorted to ground
- Internal sensor short
- 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 read TCM live data for shift fork D position to see when the signal went low and whether the fault is currently present.
- With the vehicle safely parked, inspect the fork D sensor connector and harness for corrosion, damaged insulation, pin damage, or contact with ground.
- Check the sensor's power and ground connections and measure the fork D signal against the manufacturer's specification.
- With power isolated as directed by the vehicle service information, check whether the fork D signal wire is shorted to ground.
- If wiring and connections pass, test the fork D position sensor for an internal short and replace it if it fails the manufacturer's test.
Common fixes
- Clean and secure corroded or loose fork D sensor connector pins.
- Repair a fork D signal wire shorted to ground or damaged harness section.
- Replace a fork D position sensor that tests internally shorted.
Can I keep driving?
Avoid driving if shifts are harsh, slipping, or the transmission is stuck in one gear; the TCM may be unable to confirm fork D engagement, and further gear changes could worsen transmission damage. If symptoms are absent, limit driving to a short trip for diagnosis.
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.