Common Problems with the
2012 Lexus GS (Mk4)

The hydraulic brake actuator used on hybrid GS models can develop excessive pump cycling, presenting as a humming or barking noise from under the bonnet when the brake pedal is released. Complete actuator failure causes long pedal travel and loss of power assistance, with repair bills frequently exceeding £1,500.

Dust, pet hair and road grime accumulate on the hybrid battery intake filter behind the rear seats on GS 300h and GS 450h models. A blocked filter reduces airflow to the nickel-metal hydride pack, triggering a Hybrid System Fault warning and, if ignored, causing the battery to overheat and degrade prematurely. Regular filter cleaning is the standard preventive fix, while a failed battery replacement is expensive.

The rear brake caliper slider pins on the GS Mk4 can seize due to road salt and moisture ingress, particularly on cars used for short urban trips where the brakes do not reach self-cleaning temperatures. This causes uneven pad wear, a dragging brake, reduced fuel economy and MOT failure. Sticky rear calipers are a common age-related annoyance on executive saloons kept in damp UK conditions.

Higher-spec GS Mk4 models fitted with Adaptive Variable Suspension can develop leaking dampers as the seals perish with age. Oil mist on the shock absorber body, a bouncy ride and uneven ride height are typical signs. OEM AVS dampers are expensive to replace, making this a costly repair on high-mileage executive saloons.

Pre-facelift GS Mk4 models use Lexus's mouse-like Remote Touch controller to operate the central infotainment screen. The controller mechanism wears over time, producing laggy cursor movement, skipped inputs and occasional screen freezes. Screen delamination can also occur on pre-2014 cars, reducing readability in bright sunlight.