P0990 code meaning
Transmission Fluid Pressure Sensor/Switch E Circuit High
What P0990 means
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.
P0990 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyHard
- Typical labor1.5 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0990
- No warning light, code stored only
- Intermittent occurrence without noticeable symptoms
- Shift quality declines over time
Common causes of P0990
- Most likelySwitch 5 stuck open by a damaged film or debris
- PossibleR1/4-5-6 regulator valve not moving, switch stays pressurised
- Less likelySignal circuit shorted to voltage or open inside the module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Tfp sensor eWiring harnessTCM
What each part of P0990 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 9 | Area: transmission. |
| 90 | The exact fault in that area. |
What to do next
- Note P0990 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0990
What does P0990 mean?
P0990 means "Transmission Fluid Pressure Sensor/Switch E Circuit High". Pressure switch E reads high, meaning pressure, when it should be vented. It is a generic code, so it means the same on every make.
Is it safe to drive with P0990?
P0990 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P0990 fail an emissions test?
P0990 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P0990 to fix?
Difficulty: hard. A typical repair takes 1.5 to 5 hours of work. This is a job for a workshop.
Will P0990 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.