Powertrain, generic · Transmission

P0991 Transmission Fluid Pressure Sensor/Switch E Circuit Intermittent

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

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.

Likely causes

Loose or corroded contact at the valve body module connector
Debris or damaged diaphragm film making the switch contact flicker
Chafed internal harness that shorts or opens under vibration
Fault in the transmission control module input stage

Symptoms

  • Stored fault, often without warning light
  • Occasional harsh or flared shift
  • Shift adaptation frozen

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
Time1–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

tfp sensor ewiring harnesstcm

Related codes

P0987P0988P0989P0990P0996

References: saabwisonline.com, gsi.ext.gm.com, law.cornell.edu.