Gearbox and clutch
Automatic gearbox jerks: causes and what to do
Jerks or thumps when an automatic changes gear usually come from the gearbox fluid (level, age or type), a solenoid or the hydraulic unit, or a gearbox that needs an adaptation. If it locks into one gear, it is in limp mode.
See a garage soonGearbox and clutch
Reviewed by Daniel Morales, founder of Reprorace SL, on
Is it serious? Can I keep driving?
Carefully, and only as far as the garage. Get to a garage soon, driving gently and without towing or loading the car. If the gearbox warning light comes on, it slips or will not engage, do not keep forcing it: the fault can get much worse.
A careful, general answer: only someone who inspects the car can say whether it is safe to drive. When in doubt, stop somewhere safe and call for assistance.
Most likely causes
- Gearbox fluid: degraded, at the wrong level or of a type not specified.
- Solenoids or hydraulic unit: they control each shift; a fault gives thumps or late shifts.
- Adaptations: after a disconnected battery or a repair, some gearboxes need to relearn.
- Torque converter or clutches: vibration at constant speed or slipping.
- Engine fault: a misfire or a torque fault can feel like a gearbox jerk.
Listed from more to less common in general; on your car they may be different. A fault-code reading and a check at the garage confirm which one it is.
To understand it better: What does a pending, stored or permanent code mean? What is live data and what is it for?
Car system: Transmission
What you can check yourself
Note in which gears and at what temperature it happens, and whether it is when shifting up or down.
Check whether the gearbox or engine warning light comes on.
Check the service schedule for a planned gearbox fluid change.
Do not try to check the gearbox fluid level yourself: on many cars it needs a workshop procedure.
Safe checks only: with the engine off and cold whenever you look under the hood, without taking anything apart and without touching hot or moving parts.
Related fault codes
- P0700Transmission control system: MIL illumination requested
- P0730Incorrect gear ratio
- P0731Gear 1: incorrect ratio
- P0732Gear 2: incorrect ratio
- P0741Torque converter clutch, circuit: performance or stuck off
- P0750Shift solenoid A: malfunction
- P0715Input/turbine shaft speed sensor A, circuit: malfunction
Generic codes that often come with this symptom. Seeing one does not confirm the cause: it is where the diagnosis starts.
How the ECO-LITE helps diagnose it
Plugged into the OBD socket, the ECO-LITE reads the fault codes of the control units that answer, with the freeze-frame data captured when the fault happened, and shows live data on your phone or computer. With your permission, your garage can see them remotely before you bring the car in.
What to look at here: gearbox control unit codes, engaged gear, gearbox fluid temperature and turbine speed, if the car reports them.
Frequently asked questions
Is automatic gearbox fluid never changed?
Some manufacturers call it lifetime fluid, but many specialists recommend changing it with use. Follow the service schedule and ask your garage.
What does it mean if it stays in third?
It is limp mode: the gearbox protects itself in a fixed gear. Read the code to find out why.
Which codes usually appear?
P0700 means the gearbox control unit has stored a fault; P0730 to P0735, an incorrect ratio in a gear; P0750 onwards, solenoids.
Keep reading
- Transmission: how it works and what fails
- Car loses power: what limp mode is
- Gears hard to engage or grinding: causes and what to do
- Car jerks when accelerating: causes and what to do
- Car symptoms: what they mean and what to do
- Check engine light on: what to do
- How to read and clear your car's fault codes
- OBD fault codes: what each one means