P0988Transmission Fluid Pressure Sensor/Switch E Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- Range/performance fault of transmission fluid pressure sensor or switch E: the signal is electrically valid but does not fit the commanded clutch state or the pressure expected from other inputs. No manufacturer documents this code publicly. GM's 6T70/6T75 family, the one public user of switch E (switch 5 on the low/reverse and 4-5-6 regulator valve), folds such plausibility checks into P0989 and P0990; its switch logic table shows which gears should pressurise the switch. Sonnax describes how these normally closed film switches in the valve body module fail through debris or delaminated films. CARB requires rationality checks of transmission inputs. Siblings: P0987 circuit, P0989 low, P0990 high.
- What you may notice
- Often no noticeable symptom at first
- Shift quality worsens because adaptation stops
- Warning light depending on manufacturer
- Likely causes
- LikelyDamaged or delaminated switch film, switch reacts late or not at all
- PossibleDebris in the fluid holding the switch or its regulator valve
- PossibleLow fluid level or real pressure deviation in the clutch circuit
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €200 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.