Powertrain, generic · Transmission

P0990 Transmission Fluid Pressure Sensor/Switch E Circuit High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Pressure switch E reads high, meaning pressure, when it should be vented. GM's 6T70/6T75 family uses E for switch 5 on the R1/4-5-6 clutch regulator valve; applying the low/reverse or 4-5-6 clutch moves that valve and should exhaust the switch. If the signal stays high after such an apply, with commanded clutch pressure at 700 kPa or more, the module counts it: 15 counts on the Saab 9-4X, 30 in GM's 2016 table. It is a Type C or Special No Trip code, so no MIL, and the adaptations of both clutches are frozen. According to Saab, normal debris in the fluid can set it intermittently without noticeable symptoms. A short to voltage on the signal wire has the same effect. P0989 is the stuck-low case.

Likely causes

Switch 5 stuck open by a damaged film or debris
R1/4-5-6 regulator valve not moving, switch stays pressurised
Signal circuit shorted to voltage or open inside the module

Symptoms

  • No warning light, code stored only
  • Intermittent occurrence without noticeable symptoms
  • Shift quality declines over time

Repair estimate

DifficultyHardWorkshop job
Parts and labour€300–1,500
Time1.5–5 h

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

Parts involved

tfp sensor ewiring harnesstcm

Related codes

P0987P0988P0989P0971P0873P0878

References: saabwisonline.com, gsi.ext.gm.com, gsi.ext.gm.com.