Code P0750: automatic gearbox shift solenoid A fault

Original definition (SAE J2012): Shift Solenoid "A" Malfunction^[1][2][3]

• P0750Shift solenoid “A”: circuit malfunction.
• P0755Shift solenoid “B” circuit fault.^[4][9][10]
• P0760Shift solenoid “C” circuit fault.^[5][11]
• P0765Shift solenoid “D” circuit fault.^[6][12]
• P0770Shift solenoid “E” circuit fault.^[7][13]

1. 1Gearbox oil (ATF) at a very low level, dirty, burnt or contaminated, which blocks the solenoid or makes it stick. It is the first cause in the list in CódigosDTC and TroubleCodes.net, and AutoDTCs places it third.^{[1][2][3][14]}
2. 2Solenoid wiring or connectors damaged, corroded, loose or open (open circuit, short to earth or with a neighbouring circuit).^{[1][2][3][14]}
3. 3Faulty solenoid “A”: open coil, internal short circuit or seized, or stuck and damaged over time.^{[1][2][3][14]}
4. 4Valve body or hydraulic passages blocked by debris, or an internal hydraulic fault that prevents the solenoid from seating or holding pressure.^[1][2][3]
5. 5Blocked gearbox oil filter.^[2]
6. 6Internal mechanical fault in the gearbox.^[3]
7. 7Gearbox or engine control unit with a faulty control circuit. TroubleCodes.net considers it very rare.^[1][3][14]

• Engine fault warning light on.^{[1][2][3][14]}Engine warning light: faults that cause it
• Limp mode: the gearbox stays in a single gear (AutoDTCs cites 3rd or 4th) and does not shift.^[1][2][3]Limp mode: faults that cause it
• Abrupt, erratic or wrong-gear shifts, with the engine revving high or stuck in a low gear; delayed engagement when selecting D or reverse.^[1][3][14]Gears will not engage: faults that cause it
• Gearbox slipping and overheating of the gearbox oil.^[2][3]
• Higher fuel consumption.^[2][3][14]Uses more fuel: faults that cause it

1. 1Read all the control units and save the freeze frame data (gear, speed, oil temperature) before clearing anything. Deal first with other solenoid, relay, gear ratio or pressure codes, and check the model's technical bulletins.^[1][2]
2. 2Check the level and condition of the gearbox oil. Correct any oil problem before replacing electrical parts; if it is very dirty, change the oil and the filter.^[1][2][3]
3. 3Inspect the gearbox wiring and connectors, and repair or replace anything damaged.^[1][2][3]
4. 4With the ignition off, measure the solenoid coil's resistance and compare it with the manufacturer's specification (AutoDTCs cites about 11 to 15 ohms in most designs and 20 to 30 in some) and with that of the other shift solenoid in the same block.^[1][14]
5. 5With the control unit and the solenoid disconnected, check the continuity of the control wire to the control unit, and that there is no short to earth or to neighbouring circuits. AutoDTCs recommends using a connector adapter rather than probing from behind.^[1]
6. 6Activate and deactivate the solenoid with the diagnostic equipment. If the solenoid, connectors and wiring check out and the code returns, check the control unit's terminals and then suspect its control circuit.^[1]
7. 7With the sump removed, look for debris and metal particles: they may indicate a mechanical fault that requires repair or replacement of the gearbox. The valve body is replaced or repaired only if the tests point to it.^[2][3]