Cause
Internal transmission leak
Fluid leaking inside the transmission — past a seal, a sealing ring or a valve body gasket — so pressure intended for one circuit escapes into another. Nothing appears on the ground, which is what separates this from an external leak and makes it far harder to find.
The result is a circuit that cannot hold pressure while the pump is working correctly. A clutch that will not apply fully slips, generates heat and stores a ratio or pressure code, and the module often compensates by raising line pressure — so the fault is masked until the compensation runs out.
The distinction from low fluid is worth making early. An internal leak has a correct fluid level and a pressure that will not build; low fluid has both. Check the level properly first, by the manufacturer's procedure and at the right temperature, since the level is meaningless read cold on most modern units. Then measure line pressure against specification — a pressure that falls away under load with a healthy pump is internal, and the sealing rings on the drums or the valve body gasket are the usual places.
Typically specialist work. Needs equipment or training most home workshops do not have.
Some of these codes mean you should stop driving
1 of the 3 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (3)
Codes where this is a likely explanation first, rather than merely a possible one.
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.
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