Parts for your 2019 Mitsubishi Asx-Brake booster

2019 Mitsubishi ASX brake booster — purpose and service advice

Technical sources confirm the 2019 Mitsubishi ASX is fitted with a vacuum-assisted brake booster. The Mitsubishi Motors Service Manual for ASX/RVR/Outlander Sport (GA2W/GA4W), Group 35A—Brakes (Power Brake—Vacuum Type, 2017–2020 coverage), details the vacuum servo arrangement on petrol models. The Mitsubishi ASA electronic parts catalogue for 2019 AU/NZ VIN ranges also lists a dedicated brake booster assembly and in-line check valve for GA2W vehicles. MMAL technical training material further references vacuum power brake units across ASX petrol variants. So, for a 2019 ASX, the brake booster is absolutely relevant and part of the standard braking system.

In day-to-day driving, the booster’s job is to use engine vacuum to multiply pedal effort, so stopping feels light and confident rather than heavy or wooden. It sits on the firewall between the brake pedal linkage and the master cylinder. A one-way check valve and vacuum hose under the bonnet keep the unit charged with vacuum, even when the engine load changes.

It’s not a scheduled replacement item, but it should be checked during routine brake services. Good workshops will inspect the vacuum hose and check valve for cracks, perishing or loose clamps, listen for a faint hiss at the firewall, and look for signs of brake fluid tracking from the master cylinder into the booster (which can damage the diaphragm). A quick function check helps too: with the engine off, the pedal is pumped until firm, held down, then the engine started—if the booster’s healthy, the pedal will drop slightly as vacuum assist kicks in.

Common symptoms of a failing booster include a hard brake pedal, longer stopping distances, a hiss when the pedal’s pressed, or a brief rise in idle speed during braking. If any of that shows up, owners should avoid long trips and book the vehicle in. Replacement involves disconnecting the master cylinder from the booster, removing the pushrod clip at the pedal, and unbolting the booster from the firewall. After fitting a genuine-spec unit, the pedal free play and brake light switch must be adjusted to spec, and the system road-tested. While there’s no fixed kilometre interval, inspecting the booster and vacuum plumbing at each service (or at least every 12 months/15,000 km) is smart practice for an ASX that brakes like it should.

• Tip: Always replace a dodgy check valve or cracked hose when doing booster work—it’s cheap insurance for consistent pedal feel.

Popular questions

What are the signs the 2019 ASX brake booster is failing?
Typical signs are a hard pedal, longer stopping distances, a hissing noise at the firewall, or the idle flaring slightly when the brake is applied. If any of these appear, it’s time for a proper inspection of the booster, check valve and vacuum hose.

How often should the brake booster be replaced?
There’s no set interval—it’s replaced on condition. During regular servicing, mechanics should inspect the vacuum hose, check valve and for any fluid ingress. If the diaphragm or valve is compromised, replacement is the reliable fix.

Is it safe to drive with a faulty brake booster?
The car will still have brakes, but without assist the pedal becomes very heavy and stopping distances can increase. For safety, short local drives only and get it booked for diagnosis and repair as soon as possible.