Shift solenoid B fault.
P0755 — also written PO755, P 0755, 0755 — is the OBD-II code for shift solenoid 'b'. Same code, same fix: this page covers every spelling of it.
P0755 is telling you the 'B' solenoid—basically an electric tap inside the gearbox—isn't doing its job. Usually hits the Vauxhall Insignias and older Toyota RAV4s hardest when the transmission fluid gets 'clarty'.
P0755 is a transmission fault code, typically costing £200–£1000 to put right in a UK garage.
What P0755 actually feels like to drive
- The car feels like it’s been 'rear-ended' when it tries to shift into 2nd or 3rd gear.
- Stuck in 'Limp Home' mode, usually holding 3rd gear so it's sluggish as a week-old brew off the lights.
- The 'Service ESC' or 'Check Gearbox' light is staring you in the face on the dash.
- Engine revs high like the clutch is slipping, then bangs violently into gear.
- Shifts perfectly when the engine is stone cold, but starts playing up after 15 minutes of driving.
What causes P0755?
- Solenoid failure
UK vehicles that throw P0755 most often
- Vauxhall Insignia A 2.0 CDTi (AF40-6 transmission) 2008-2015
- Toyota RAV4 2.0 VVTi (U140 series box) 2000-2005
- Ford Focus 2.0 Petrol (4F27E auto) 2005-2011
- Volvo V70/S60 2.4D (TF-80SC box) 2006-2013
- Vauxhall Astra J 1.4 Turbo (6T40 transmission) 2009-2015
- Land Rover Freelander 2 TD4 (Aisin Warner box) 2006-2014
How P0755 is fixed
- Solenoid replacement
The P0755 misdiagnosis that wastes money
I see it time and again: a lad brings in a car after spending £400 on a brand new valve body or a full gearbox flush because some forum told him to. Nine times out of ten on these boxes, it's not the metalwork failing; it's the internal wiring loom inside the transmission getting brittle from the heat or a dirty multi-plug connector behind the nearside wheel arch. People throw solenoids at it, but if the wiring is shot, that P0755 will pop back up before they've even cleared the forecourt.
What a UK garage should charge for P0755
A basic diagnostic hook-up should be £60 to £90. If it’s just one solenoid, you're looking at £250 to £450 including fresh ATF (Automatic Transmission Fluid). However, on some boxes like the GM 6T40, the solenoids are part of a 'TEHCM' unit—that’s a £900 job easily. Always use genuine Bosch or OE parts; the cheap Chinese solenoids from eBay 'dead on arrival' more often than not. Main dealers will likely just quote you £3,000 for a replacement gearbox because they don't like getting their hands oily inside the casing.
P0755 repair cost in the UK
Most P0755 repairs land between £200–£1000 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Bob's tip on P0755
Don't let a garage tell you it needs a 'recon box' right away for two grand. If they haven't done a resistance test at the TCM (Transmission Control Module) connector, they're guessing with your wallet. Insist on a 'live data' road test to see if the Solenoid B command is actually being sent. If the car is an Astra or Insignia, ask them to check the pins for corrosion first—it's a ten-minute job that can save you £800. If it's a 'sealed for life' unit, ignore that marketing rubbish; the oil is likely black and thick, which is what killed the solenoid in the first place.
Can you drive with P0755?
Erratic shifting.
Urgency: high.