Symptom

One gear slips while the others are fine

The car drives normally except in one particular gear, where the revs rise without matching road speed or the change never quite completes. Which gear it is narrows the fault further than almost anything else a driver can report, because an automatic makes each ratio by holding a different combination of clutch packs and brake bands — so a single bad ratio points at the one element that gear does not share with its neighbours, while everything relying on the others stays perfect. Say which gear and whether it is worse hot; a gearbox that misbehaves in third alone is a much smaller job than one that slips everywhere.

Also described as: slips in one gear, third gear slips, only one gear is bad, revs up in one gear, gear slipping but others fine, فقط یک دنده خلاص میکند, دنده سه خلاص میکند, una marcha patina, solo falla una marcha, patina en tercera, غيار واحد يزحلق, مشكلة في سرعة واحدة فقط, الثالث يفلت

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What this usually means

Which gear it is narrows the fault further than almost anything else a driver can report. An automatic makes each ratio by holding a different combination of clutch packs and brake bands, so a single bad ratio points at the one element that gear does not share with its neighbours — while everything relying on the others stays perfect.

That is why this complaint is good news relative to general slipping. A gearbox slipping everywhere is a pressure or fluid problem, or a worn-out transmission. A gearbox slipping in third alone has one element at fault, and the surrounding ratios are evidence that pressure, fluid and pump are all still doing their jobs.

The population for a single ratio is short: the friction material in that clutch pack or band, the seals in its drum or servo, the solenoid that applies it, or the valve bore in its circuit. Worse when hot points at pressure — a seal or a bore leaking more as the fluid thins. Equally bad cold and hot points at the friction material itself.

Say which gear and whether it is worse hot. Those two facts do more to shorten the diagnosis than any amount of road testing by somebody who was not told them, and a gearbox that misbehaves in one ratio alone is a much smaller job than one that slips everywhere.

Do not put off the diagnosis on the grounds that the car still drives. A slipping element polishes and burns its own material and contaminates the fluid every other element depends on, so a single-ratio fault left alone becomes a whole-gearbox fault.

Working through it

What you find	Likely cause	How to confirm it	What fixes it
Slips in one gear, worse once hot	Pressure at that element — a seal in its drum or servo, or a worn valve bore leaking as the fluid thins	Measure line pressure hot and cold. Note the gear precisely and whether the slip appears at engagement or under load.	Repair the seals or service the valve body circuit for that element.
Slips in one gear equally cold and hot	The friction material in that clutch pack or band is worn	Temperature independence is the discriminator. Look for material in the pan and on the magnet.	Overhaul that element. Pressure work will not restore worn material.
That gear is missing entirely rather than slipping	The solenoid or circuit that applies it, rather than the friction element	Command the solenoid on a scan tool and watch for a response. Absent is a different fault from weak.	Renew the solenoid or repair its circuit, then relearn adaptation.
Slipping spread to other gears over time	Debris and burnt fluid from the failing element are now affecting the rest	Inspect fluid condition and the pan. Progression from one ratio to several is the pattern.	Overhaul rather than repair the single element. This is the cost of leaving it, and it is why the brief argues against waiting.
Fluid level and condition good, one gear still slipping	Genuinely a single-element fault rather than a system one — the good news case	Healthy neighbouring ratios are the evidence that pump, pressure and fluid are all fine.	Repair the named element. Do not condemn the transmission on one ratio.
Slipping in reverse only	Reverse's own clutch or band and its own solenoid circuit — losing it alone does not mean the transmission is finished	Note whether the reverse lights still work, which separates an electrical selector fault from a hydraulic one.	Repair the reverse element or its circuit. This has its own entry in this vocabulary.

Slips in one gear, worse once hot

Likely cause

Pressure at that element — a seal in its drum or servo, or a worn valve bore leaking as the fluid thins

How to confirm it

Measure line pressure hot and cold. Note the gear precisely and whether the slip appears at engagement or under load.

What fixes it

Repair the seals or service the valve body circuit for that element.
Slips in one gear equally cold and hot

Likely cause

The friction material in that clutch pack or band is worn

How to confirm it

Temperature independence is the discriminator. Look for material in the pan and on the magnet.

What fixes it

Overhaul that element. Pressure work will not restore worn material.
That gear is missing entirely rather than slipping

Likely cause

The solenoid or circuit that applies it, rather than the friction element

How to confirm it

Command the solenoid on a scan tool and watch for a response. Absent is a different fault from weak.

What fixes it

Renew the solenoid or repair its circuit, then relearn adaptation.
Slipping spread to other gears over time

Likely cause

Debris and burnt fluid from the failing element are now affecting the rest

How to confirm it

Inspect fluid condition and the pan. Progression from one ratio to several is the pattern.

What fixes it

Overhaul rather than repair the single element. This is the cost of leaving it, and it is why the brief argues against waiting.
Fluid level and condition good, one gear still slipping

Likely cause

Genuinely a single-element fault rather than a system one — the good news case

How to confirm it

Healthy neighbouring ratios are the evidence that pump, pressure and fluid are all fine.

What fixes it

Repair the named element. Do not condemn the transmission on one ratio.
Slipping in reverse only

Likely cause

Reverse's own clutch or band and its own solenoid circuit — losing it alone does not mean the transmission is finished

How to confirm it

Note whether the reverse lights still work, which separates an electrical selector fault from a hydraulic one.

What fixes it

Repair the reverse element or its circuit. This has its own entry in this vocabulary.

Codes that produce this symptom (7)

Listed with the codes that most typically present this way first — the likeliest place to start.

Information, not instruction

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.

Others with this symptom

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