Symptom
Engine speed rises without a matching increase in road speed. Degraded or overheated fluid is a common cause, and continued driving accelerates the damage.
Also described as: slipping, gearbox slipping, revs flare, engine revs but no drive, loss of drive, slipping clutch, گیربکس خلاص میکند, دنده در نمیرود, گیربکس لیز میخورد, caja patina, transmision patina, embrague patina, revoluciones suben y no avanza, الجير يزحلق, ناقل الحركة يفلت, الدورات ترتفع بدون تسارع
22 of the 281 codes that produce this symptom indicate a fault where continuing to drive risks damage or is unsafe. If the symptom is sudden or severe, treat it as one of those until a scan says otherwise.
Engine speed rising without a matching increase in road speed means a clutch or band is not holding, and every mile driven that way makes it worse. A slipping friction element generates heat exactly where the fluid cannot carry it away quickly, and that heat destroys both the material and the fluid. This is one of the few transmission complaints where continuing to drive genuinely changes the repair, so the honest advice is to stop using it for anything but reaching help.
Fluid is the first thing to establish, and it is diagnostic in both directions. Low fluid means the pump cannot make pressure, so elements that should be clamped are merely touching. Burnt fluid means slipping has already been happening — the smell is the friction material, and it tells you the damage is not hypothetical.
There is a genuine disagreement about servicing a badly neglected high-mileage transmission, and it deserves stating rather than resolving. The mainstream position is that fresh, correct fluid can only help. Japanese trade sources disagree specifically for boxes that have run 80,000 km or more without a change, on two mechanisms: the friction characteristics of new fluid may not match clutch material already worn to the old fluid, and the detergency of fresh fluid can dissolve deposits that then block the small passages and valves in the valve body. Both sides agree on the practical point — a transmission that is already slipping is not rescued by a fluid change, and the decision is about whether one might make a marginal box worse rather than about whether fluid matters.
Where the slip happens is the most useful thing a driver can report. Slipping in every gear points at pressure — fluid level, the pump, or a leak the whole system shares. Slipping in one gear points at the element that gear alone uses, which is a much smaller job.
| What you find | Likely cause | How to confirm it | What fixes it |
|---|---|---|---|
| Revs rise without acceleration in every gear | Line pressure — low fluid, a failing pump, or a leak common to the whole system | Check level by the manufacturer's procedure at the specified temperature, then measure line pressure against specification. | Correct the level, or repair the pump or leak the pressure test names. Stop driving it meanwhile. |
| Slips in one gear only, others normal | The clutch pack or band that gear alone uses | Establish exactly which gear and whether it is worse hot. That narrows the fault to elements not shared with neighbouring ratios. | Repair the named element. Far smaller than a gearbox that slips everywhere, which is why the observation matters. |
| Fluid smells burnt or is very dark | Friction material already overheated — slipping has been happening for some time | Smell and colour against a fresh sample. Look for material in the pan or on the magnet when it is opened. | Overhaul. A fluid service will not restore a clutch that has already been cooked. |
| Slipping appeared shortly after a fluid change on a neglected high-mileage box | Disputed — friction mismatch with worn material, or dissolved deposits blocking valve passages | Establish the service history and what fluid was used. Note that sources disagree about whether the change caused this or merely coincided with it. | Verify the fluid specification is correct first. Where passages are blocked, a valve body service is the route; where material is worn, an overhaul. |
| Slips only when hot, normal from cold | Clearances and pressures at temperature — worn elements or a pump that cannot maintain pressure hot | Measure line pressure hot as well as cold. A cold test on this fault passes and proves nothing. | Repair on the hot measurement. Check the cooler and its lines while there, since heat is what got it here. |
| Revs rise between ratios but hold once engaged | A flare during the change rather than general slipping — a narrower fault with its own entry | Separate the two: a flare is momentary and tied to a shift; slipping persists in gear. | Diagnose as a flare on the specific change rather than as whole-gearbox slipping. |
Revs rise without acceleration in every gear
Slips in one gear only, others normal
Fluid smells burnt or is very dark
Slipping appeared shortly after a fluid change on a neglected high-mileage box
Slips only when hot, normal from cold
Revs rise between ratios but hold once engaged
Listed with the codes that most typically present this way first — the likeliest place to start.
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
The corpus describes transmission slip as engine speed rising without a matching increase in road speed, and says to treat it as a fault. On a CVT that is the normal, designed beha...
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