Common Problems with the
2004 Proton GEN-2

The 1.6-litre CamPro S4PH engine utilizes an electronic throttle body assembly that is prone to oil mist and carbon contamination from the positive crankcase ventilation (PCV) system. Over time, gummy carbon deposits accumulate around the throttle butterfly plate and idle bypass bore. This disrupts the airflow calculations of the engine control unit (ECU), causing erratic idle hunting between 600 rpm and 1,300 rpm, delayed throttle response when pulling away, and sudden engine stalling when dipping the clutch at roundabouts or traffic lights. Cleaning the throttle assembly and performing an ECU idle relearn procedure is required to restore smooth operation.

The Proton GEN-2 is equipped with rear solid disc brakes that incorporate an internal mechanical handbrake actuator lever on each caliper. Exposed to corrosive UK road salt and road wash, the rubber slider pin dust gaiters split and allow moisture into the guide bores. This causes the steel pins and internal handbrake return springs to corrode and seize. As a result, the rear brake pads drag persistently against the rotor, generating excessive brake dust, overheating the rear hubs, and leading to MOT failures for inadequate parking brake efficiency or brake effort imbalance exceeding 30 percent.

While Lotus tuned the GEN-2 suspension for crisp roadholding, British speed bumps and severe winter potholes place immense stress on the front MacPherson strut assemblies. The protective plastic coating on the front coil springs chips easily from road grit, allowing road salt to initiate rust pitting along the lower pig-tail coils, which eventually fracture under compression. Concurrently, the front anti-roll bar drop link ball joints and mounting bushes wear out quickly, generating metallic rattling noises over broken road surfaces and leading to an immediate UK MOT test failure.

The five-speed manual transmission linkages on the Proton GEN-2 rely on rubber and nylon pivot bushings beneath the cabin centre console and along the underbody selector rods. Due to heat from the exhaust tunnel and road grime ingress, these bushings degrade, perish, and develop excessive slop. The gear selector lever loses its positive spring-loaded gate definition, resulting in an imprecise, vague shift action, difficulty selecting first gear or reverse from neutral, and occasional gear crunching into second. Replacing the worn bushings with uprated polyurethane or new factory nylon bushes restores shift precision.

The electrical wiring harness routed from the cabin body through the front A-pillar rubber accordion gaiters to the doors is prone to copper wire fatigue. Repeated opening and closing of the driver door causes the stiff insulation to crack and inner conductors to fracture. Additionally, the internal electric motor solenoids inside the door latch mechanisms gum up with dried grease. This results in intermittent or complete failure of the central locking system, doors bouncing back to unlocked after arming with the key fob, and erratic power window or electric door mirror operation.