P0991Transmission Fluid Pressure Sensor/Switch E Circuit Intermittent
- Generic OBD-II code · Powertrain
- How the car detects it
- The module has seen the signal of the fifth transmission pressure sensor or switch drop out or jump briefly, without a steady low or high reading. No manufacturer documents this code publicly. The only switch E found in public sources is GM's TFP switch 5 in the 6T70/6T75 valve body module (Saab 9-4X 2011), a normally closed switch that GM monitors only through P0989 and P0990: signal stuck low at commanded pressure of 50 kPa or less, or stuck high, counted over clutch releases and logged as Special No Trip without MIL. An intermittent check would follow the CARB rule that transmission inputs be monitored for circuit faults. Steady faults are P0987 to P0990. Expect frozen shift adaptation and the odd harsh shift.
- What you may notice
- Stored fault, often without warning light
- Occasional harsh or flared shift
- Shift adaptation frozen
- Likely causes
- LikelyLoose or corroded contact at the valve body module connector
- PossibleDebris or damaged diaphragm film making the switch contact flicker
- PossibleChafed internal harness that shorts or opens under vibration
- RareFault in the transmission control module input stage
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.