What does it mean?
P1759 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: A/T FR/B Solenoid Valve Performance . This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms
- Slipping with engine RPM rising while road speed stays flat
- Missing or very delayed engagement in the affected gears
- Harsh, banging shifts as the module raises pressure to compensate
- MIL (check engine lamp) on with a transmission warning lamp
- Burnt fluid smell and quickly rising transmission temperature
- Limp mode and a serious loss of drive if the slip continues
Likely causes
- Solenoid valve stuck, slow or leaking internally because of varnish and debris
- Worn front brake clutch pack that can no longer hold torque
- Low line pressure from low fluid, a worn pump or an internal leak
- Contaminated ATF with a clogged filter and blocked solenoid screens
- Worn valve body bore or a damaged separator plate gasket bleeding pressure
- Electrical fault in the solenoid circuit such as high resistance or an intermittent open
- Hardened piston seals in the apply circuit letting pressure escape
How to fix it
- Stop driving if the transmission is slipping badly, since continued slip destroys friction material
- Check fluid level, colour and smell, and inspect the pan magnet for clutch material
- Log gear command against calculated ratio on live data to confirm which element slips
- Connect a pressure gauge and compare line and circuit pressure with specification
- Command the solenoid with a scan tool and measure its resistance at the case connector
- Remove the valve body and check the solenoid, screens and valve bores for varnish and debris
- Replace the solenoid or valve body, and overhaul the clutch pack if the friction plates are worn