It only does it when I accelerate hard. Why does driving gently hide it?

Because gentle driving never asks the third-gear friction element to hold much torque. An element with worn material or slightly low apply pressure has enough grip for light loads and runs out of it under real power. That pattern is genuinely informative: it points at holding capacity — pressure, or the element itself — rather than at the electrical control of the shift, which would misbehave regardless of how hard you were pushing.

What is the difference between a flare and a bind on this shift?

They are the two ways the same overlap can go wrong. On most transmissions the 2-3 change requires one element to release as another applies. If the release happens too early, nothing is holding for an instant and engine speed jumps — a flare. If the release happens too late, both are applied at once and the transmission momentarily fights itself, which you feel as a tug or a light braking sensation — a bind. Telling a technician which one it does saves real diagnostic time.

Does one bad shift mean the transmission is finished?

It usually argues the opposite. The pump, the fluid supply, general line pressure, the torque converter and the speed sensors are involved in every shift. If any of those were the problem, more than one shift would be wrong. A fault confined to 2-3 points at what is unique to that event — its solenoid, its valve, and the two elements that hand over — which is a far smaller and cheaper set of parts than a rebuild.

How long can I keep driving it?

Not long, and how you drive matters more than how far. A slipping element generates heat and sheds friction material into the fluid, which then circulates through the valve body and makes the hydraulic side worse. Since this particular fault is triggered by load, keeping the throttle light genuinely reduces the damage while you get it looked at — but it is a way of buying a few days, not a way of living with it.

OBD-II trouble code

P0782: 2-3 Shift Malfunction

The change from second to third did not produce the expected ratio. On most transmissions this is the first shift that requires one element to let go while another takes hold — and that overlap is what makes it fail differently from the shifts below it.

High severityPowertrainTransmission / Shift ControlDrivable short-term

Quick facts

System: Powertrain
Category: Transmission / Shift Control
Severity: High severity
Drivable: Usually safe to drive short-term
Repair cost range: $150 – $4,000
DIY difficulty: Shop recommended

What does P0782 mean?

The controller commanded the change from second gear to third, compared input shaft speed against output shaft speed, and did not see the ratio it expected inside the window it allowed. That much P0782 shares with every other named-shift code. What separates it is the mechanical event it describes.

Moving off from a stop is mostly a matter of applying things. On a great many automatic transmissions the 1-2 change is a straightforward apply — an element that was not doing any work is brought into play, and if it applies a fraction slowly the shift is merely soft. The 2-3 change is usually the first one in the sequence that is not like that. It is commonly a release-and-apply: something that was holding second has to let go at almost the same instant something else takes up third, and the two events have to overlap correctly. That timing window is why this shift has failure modes the lower one simply cannot produce.

Get the overlap wrong in one direction and both elements are momentarily applied. The transmission fights itself, and the driver feels a hard tug or a brief sensation of the brakes being touched — a tie-up or bind. Get it wrong the other way and neither element is holding for a moment, so engine speed jumps while road speed does not: a flare. Both symptoms point at the same event but at opposite ends of the timing error, and knowing which one the vehicle is doing is worth a great deal before anything is taken apart.

The other thing that sets 2-3 apart is when it happens in ordinary driving. First to second usually occurs at walking pace with the throttle barely open. Second to third is typically the first shift that regularly happens with the engine actually making torque — pulling onto a main road, taking a slip road, overtaking. Torque is what exposes a friction element that is marginal rather than dead. A clutch pack with worn material or slightly low apply pressure will hold perfectly well against gentle torque and slip the moment real load arrives, which is why so many 2-3 complaints appear only under acceleration and vanish entirely when the vehicle is driven softly.

That load sensitivity is a diagnostic tool rather than a nuisance. A fault that is present at every throttle opening behaves like a control or hydraulic problem; a fault that only shows itself when you ask for power behaves like a holding-capacity problem. Establishing which of those you have, on a road test, costs nothing and narrows the search considerably.

Common causes

Mis-timed overlap between the element releasing second and the element applying third, from a worn or sticking valve in that circuit
Friction element for third gear slipping under load while holding fine at light throttle
Shift solenoid for the 2-3 event sticking, slow, or electrically faulty
Line pressure marginal at the throttle openings where this shift normally occurs
Low or degraded fluid, reducing apply pressure exactly when torque is highest
Valve body wear or debris restricting the release side of the overlap rather than the apply side
Worn band or servo, on transmissions where second is held by a band that must release for third
Accumulator or apply piston seal leaking, softening the third-gear apply
Adaptive shift pressure values learned around a fault, or never reset after previous work

Symptoms

Engine speed flaring between second and third, most obviously under acceleration
A brief bind, drag, or tug as the shift happens — the tie-up signature that lower shifts do not produce
The fault present when accelerating hard and absent when driven gently
Shift into third delayed, or not occurring at all
Every other shift feeling normal, which points away from anything shared
Transmission dropping into limp mode and holding one gear
Check engine light on, often with P0780 stored alongside
The complaint often mistaken for an engine problem, because it happens at road speed with the engine loaded

Diagnostic steps

1.Road test at two distinctly different throttle openings. A 2-3 fault that appears only under load and disappears when driven gently is a holding-capacity finding, and it is the single most useful thing you can establish before opening anything.
2.Establish whether the failure is a flare or a bind. They are opposite ends of the same overlap timing error and they lead to different parts of the circuit — a bind means something is not releasing, a flare means something is not applying in time.
3.Confirm the fault is confined to the 2-3 shift by working through the whole range. If other shifts misbehave, the problem is something they share and the diagnosis changes entirely.
4.Check fluid level and condition to the manufacturer's procedure and temperature, then look at the fluid for a burnt smell, which on a load-sensitive complaint is a strong hint that an element has been slipping for a while.
5.Identify from service data exactly which elements release and which apply for the 2-3 change on this transmission. This shift involves two elements rather than one, so the list of suspects is genuinely longer than it is for 1-2.
6.Log input and output shaft speed through the shift and look at the shape of the ratio change. A ratio that overshoots and recovers reads differently from one that never arrives.
7.Measure line pressure at the throttle opening where the fault appears, not at idle. Pressure that is adequate at light load and falls away under load explains a symptom that only shows up when you accelerate.
8.Command the solenoid with a scan tool and confirm a hydraulic response follows the electrical command, which separates a control fault from a mechanical one.
9.Drop the pan and read the magnet and filter. Friction material specific to the third-gear element supports the slipping-under-load theory; general debris points at the valve body.

Repair cost

$150 – $4,000

A fluid and filter service is $150 to $350 and does resolve a share of these, particularly where pressure was marginal rather than an element being worn out. A single shift solenoid runs $250 to $700 fitted. Valve body work is $600 to $1,400 and is a common outcome here specifically, because an overlap timing fault often lives in a valve rather than in a clutch. If the third-gear friction element has slipped under load long enough to glaze or burn, it becomes an overhaul at $2,500 to $4,000 or more. The load test and the pan inspection are what decide which of those you are looking at, and they should both happen before the upper figures are discussed.

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DIY vs shop

Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.