C1391 fault code: what it means

C1391: Abnormal leak of brake accumulator pressure on Lexus hybrids. Points to an internal leak in the brake actuator assembly (TSB L-SB-0016-16 for RX400h).

Chassis (brakes, steering, suspension) · Costly if missed

Usual causes, most likely first

internal leak in the brake actuator/accumulator
brake pump motor wear from constant cycling

C1391 by make

Lexus

Abnormal leak of brake accumulator pressure on Lexus hybrids. Points to an internal leak in the brake actuator assembly (TSB L-SB-0016-16 for RX400h).

Usual causes: internal leak in the brake actuator/accumulator; brake pump motor wear from constant cycling

Toyota

Abnormal leak of brake accumulator pressure on Toyota hybrids with an electronic brake actuator. Usually the brake actuator assembly has an internal leak.

Usual causes: internal leak in the brake actuator/accumulator; brake pump motor wearing out from constant cycling

What the repair usually costs

ABS / brake booster actuator replacement (Toyota hybrid)NZ$1,280–NZ$3,430 · A$1,140–A$3,090

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Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.