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.
Medium severity. Can I keep driving?Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
Symptoms
- No warning light, code stored only
- Intermittent occurrence without noticeable symptoms
- Shift quality declines over time
Most 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
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
What each character of P0990 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 9: Transmission
- 90: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0990?
Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
What causes code P0990?
The most common causes are: 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.
Related codes
- P0987Transmission Fluid Pressure Sensor/Switch E Circuit
- P0988Transmission Fluid Pressure Sensor/Switch E Circuit Range/Performance
- P0989Transmission Fluid Pressure Sensor/Switch E Circuit Low
- P0971Pressure Control Solenoid C Control Circuit High
- P0873Transmission Fluid Pressure Sensor/Switch C Circuit High
- P0878Transmission Fluid Pressure Sensor/Switch D Circuit High
Sources
- saabwisonline.com: dtc p0989 or p0990
- gsi.ext.gm.com: 11OBDG07 TRANS Diagnostics
- gsi.ext.gm.com: 16OBDG03 Transmission Diagnostics
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.