Broken or chafed wire in the secondary pressure solenoid circuit, often in the transmission harness near the valve body; Corroded or loose electrical connector at the transmission case pass-through or solenoid plug; Failed secondary pressure solenoid coil with an internal open winding; Damaged transmission control module driver circuit or internal fault; Contaminated or degraded transmission fluid causing solenoid coil damage over time; Rodent damage or pinched wiring along the harness route

DTC codes / BMW codes / P1751

P1751 · BMWSecondary Pressure Solenoid Open Circuit

Q: What does code P1751 mean?

Secondary Pressure Solenoid Open Circuit. P1751 on BMW vehicles means the transmission control module has detected an open circuit in the secondary pressure solenoid circuit, so no current can flow through the solenoid coil or its wiring. The computer commands a current to the solenoid and sees no expected voltage drop or current feedback, which flags the circuit as electrically open.

P1751 on BMW vehicles means the transmission control module has detected an open circuit in the secondary pressure solenoid circuit, so no current can flow through the solenoid coil or its wiring. The computer commands a current to the solenoid and sees no expected voltage drop or current feedback, which flags the circuit as electrically open.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyProfessional

AreaTransmission

Symptoms you may notice

Transmission warning light or check engine light illuminated on the instrument cluster
Harsh or delayed shifts, especially when the transmission is cold
Transmission stuck in a default gear or limp-home mode with reduced power
Slipping or flaring during upshifts and downshifts
Often no symptoms besides the warning light if the fault is intermittent

Common causes, most likely first

Broken or chafed wire in the secondary pressure solenoid circuit, often in the transmission harness near the valve body
Corroded or loose electrical connector at the transmission case pass-through or solenoid plug
Failed secondary pressure solenoid coil with an internal open winding
Damaged transmission control module driver circuit or internal fault
Contaminated or degraded transmission fluid causing solenoid coil damage over time
Rodent damage or pinched wiring along the harness route

How to diagnose and fix it

Scan all modules and record freeze-frame data to confirm P1751 is current and not a stored history code
Inspect the transmission harness and connectors for chafing, corrosion, or loose pins before any parts are replaced
Measure solenoid resistance at the transmission connector and compare with BMW specifications for the secondary pressure solenoid
Check continuity and voltage drop on both solenoid circuit wires from the control module to the transmission connector
If wiring checks pass, remove the transmission pan and valve body to test the solenoid directly and inspect for fluid contamination
Replace the faulty solenoid or repair the open circuit, then clear codes and perform a transmission adaptation reset and road test

Open circuit does not always mean bad solenoid

A large share of P1751 cases on BMW vehicles are caused by a chafed or broken wire in the transmission harness rather than the solenoid itself, so always ohm the circuit end to end before condemning the valve body.
Intermittent open circuits often set the code only when the transmission is hot or after a cold start, so a resistance test on a cold solenoid can pass while the fault is still present.
A weak or failing battery or charging system can cause the control module to log false open-circuit codes, so verify supply voltage and grounds before deep electrical testing.
Transmission fluid that has never been serviced can leave varnish on the solenoid coil and connector pins, creating high resistance that eventually reads as an open circuit.
Replacing the secondary pressure solenoid without clearing and relearning transmission adaptations can leave the vehicle shifting poorly and make a correct repair look unsuccessful.

Can I keep driving with P1751?

You can usually drive the vehicle to a workshop, but expect harsh shifts or limp-home mode and avoid heavy acceleration or towing until the circuit is repaired. If the transmission slips badly or refuses to engage a gear, stop driving and arrange a tow to prevent internal damage.

Tools that help

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Guidance is general and written for BMW vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.