P0705: How to Diagnose & Fix — Transmission Range Sensor Circuit Malfunction (PRNDL Input)

2021-2023 Legacy sedans are among the vehicles Subaru recalled under campaign WRQ-23. The defect is a weld on the park/neutral start interlock switch — the inhibitor switch — that was not made adequately, allowing water to enter the switch body and cause the switch to fail. A Legacy with a failed inhibitor switch may not light its reverse lamps and may not bring up the rearview camera image, both of which matter most when backing out of a parking space or driveway. NHTSA rates the consequence as an increased crash risk. Note that the 95,830-unit figure attached to this recall is the total for the entire campaign across every model included, not a count of Legacys.

An insufficient weld between the switch stator and cover of the transmission inhibitor (park/neutral start interlock) switch allows water intrusion over time, causing the switch to become inoperative. When it fails, the reverse lights do not illuminate and the rearview/backup camera image does not display when the vehicle is shifted into reverse, increasing the risk of a backover crash. Subaru recalled certain 2021-2023 Outback (and Legacy, plus 2021 Crosstrek and 2022 Forester) vehicles; roughly 51,470 Outbacks were among the ~95,830 total affected.

If you drive a 2022 Forester, it may be covered by Subaru recall WRQ-23. An insufficient weld in the automatic transmission's inhibitor switch (the park/neutral start interlock switch) can allow water to work its way into the switch, and a water-contaminated switch can stop working. Because the Forester uses that switch to detect that reverse has been selected, the failure shows up as the reverse lamps not illuminating and the rearview camera image not coming up on the infotainment screen. Backing up without the camera view and without reverse lights to warn people behind you raises the chance of a collision, which is why NHTSA treats this as a safety defect.

Early second-generation 200 sedans with the ZF-sourced 9-speed automatic (948TE/9HP48) can unexpectedly drop into neutral while driving, causing a sudden loss of propulsion. The root cause is insufficient crimps on the terminals of the 26-way connector in the transmission range-sensor wire harness, which corrupts the transmission's gear-position signal. This triggered NHTSA recall 16V-529 covering the 2015 Chrysler 200 alongside related Jeep Cherokee, Renegade, RAM ProMaster City, and Fiat 500X models sharing the transmission.

The Tremec TR-9080 eight-speed dual-clutch transaxle (RPO M1L) fitted to every C8 has generated a sustained pattern of failures serious enough that GM formally notified NHTSA in November 2021 that it was investigating. The signature complaint is a 'Service Transmission' message that will not clear and that prevents the car from powering off — GM attributed this to debris on the park position sensor magnet feeding an incorrect position reading to the transmission control module. Beyond that, owners report DCT fluid leaks, DCT filters found heavily contaminated well before the 7,500-mile initial service, low-speed shudder during parking-lot maneuvers and 1-2 shifts on early 2020 cars, limp-mode entry, unexpected shifts into neutral while driving, and outright transmission replacement — one NHTSA complaint documents total transmission failure at 1,400 miles, another documents the rear transaxle case cracking and dumping fluid onto the exhaust. GM went so far as to bulletin dealers in November 2021 to collect and return every DCT filter removed at the 7,500-mile service for engineering analysis. The debris findings suggest internal wear material circulating in the unit, not merely a software calibration problem.