Transmission codes: P0700, P0715, P0720, P0741, P0750
The automatic started jerking, hesitating before shifts or «slipping» on the motorway — and the scanner shows P0700. Here is what stands behind it and why P0700 on its own means nothing.
If P0700 is the only thing on your list, you have not read the transmission fault. You have read a flag saying there is one.
P0700 is not a fault
The transmission is run by its own control unit. It keeps its codes in its own memory and tells the engine only one thing: «I have a problem, light the check». The engine records that as P0700 — and that is all. The real code sits inside the transmission unit, and plain OBD-II does not reach it on every car.
That limitation is covered in detail in why a scanner does not show ABS, airbag and transmission faults. In short: the standard made only emissions-related codes mandatory. Everything else is up to the manufacturer's own protocol and goodwill.
So the first step is not to replace parts but to check whether a specific code from the list below sits next to P0700. If it does — read that one. If it does not, you need dealer-level access to the transmission unit.
Speed sensors: P0715, P0717, P0720, P0725
The gearbox has two speed sensors: input (P0715, P0717) and output (P0720, P0725). The difference between them is exactly how the unit knows which gear is engaged and whether it is slipping.
Lose the input one and the gearbox no longer knows how fast the torque converter is turning, so it shifts by a fallback schedule: hard and at the wrong moment. Lose the output one and the unit sees no speed at all, usually dropping the gearbox into limp mode with a single gear.
You can check this without access to the transmission unit. Open live data and watch engine RPM and vehicle speed at the same time. On a level road, in a fixed gear, their ratio must stay constant. If it wanders while the speed does not, something is slipping.
P0741 — torque converter lock-up
The most common and the most deceptive code. It feels like «the car does not pull on the motorway», «it holds high revs», «fuel use went up for no reason».
The torque converter is a fluid coupling: at low speed it slips on purpose so the car pulls away smoothly. On the motorway the unit locks it, connecting the engine to the gearbox directly — otherwise part of the power would forever turn into heat. P0741 means the lock-up command is sent but nothing locks.
What you can see in the app: hold a steady motorway speed and watch the revs. On a healthy car lock-up drops the revs by 150–300 rpm while the speed stays the same. No drop at all means no lock-up.
In half of the cases the cause is not mechanical: the lock-up solenoid, dirty fluid, a clogged valve body. Hence the rule — fluid first, repair later.
Solenoids: P0750, P0751, P0755, P0756
Solenoids are electrical taps inside the valve body. There are several, and the codes come in pairs: P0750, P0755 — solenoid circuit (electrics), P0751, P0756 — «stuck» (mechanics or dirt).
The difference matters more than it looks. Electrics means a connector, wiring or the solenoid itself: modest money. «Stuck» almost always means dirty fluid and wear, and the conversation is already about dropping the pan.
P0730 and P0710
P0730 — «incorrect gear ratio»: a gear engaged that was not the one asked for. That is a result, not a cause: look at the solenoids and speed sensors.
P0710, P0711 — transmission fluid temperature sensor. While it lies, the unit shifts by the wrong table: cold fluid is thick and needs a different schedule. Hence «it only jerks when cold».
What to do, in order
- Read all codes, not the first one. If a specific code sits next to P0700, work with that one.
- Check the level and the smell of the transmission fluid. A burnt smell changes the whole conversation.
- Take a freeze frame: at what speed, temperature and load it happened.
- Drive on the motorway watching revs and speed — that is how lock-up and slipping are checked.
- Put together a report for the mechanic: a gearbox that «sometimes jerks» is exactly the case that cannot be fixed without numbers.
What not to do
Clear the code and drive on. Unlike the engine, a cleared transmission code does not undo wear: a slipping clutch pack eats itself with every slip, and the fluid fills with debris that clogs the valve body. What the clear button actually does is covered in clearing a code.
If the car already jerks under acceleration or has dropped into limp mode — no faster than 60 km/h — that is no longer a «let me watch it» situation.
