My wife got some problems with a 2000 accent. Sometimes, the gas stick opened and the brake pedal get really hard like if there's no power brakes. At the same time, the check engine light flashes. It happened three times in about one year and a half. It's not really often but it's really scary when it happens. The dealer plugged the code reader and it said a lot of different possibilities like the maf and o2 sensor etc. We changed the oxigen sensor and the vacuum hose last time but did the problem again yesterday. I alsolooked atthe gas cable and everything from the gas pedal to the gas cable seems to work freely. Is it possible that something somewhere in the injection system keeps the engine pulling and stop the vaccum effect needed for the power brake at the same time. Thanks for your help andi'm sorry for my english that is not so good!

 

Re hard pedal, check the throttle body around the valve for build up of soot, oil etc. and if there is deposit it can jam the the throttle valve. Use a cleaner that is compatible with your emmision system ( some can render your 02 sensors useless) and see if that helps. Might invest in a (OBD II - cars use this protocol built from 96 on up)scanner and retrieve the codes yourself. If the check engine just flashes and does not stay on means soft codes,problems that come and go, and the codes dont always reflect the real problem. Some scanners, I use AutoXray 5000, will pick up soft codes while the scanner is hooked up and the car being driven. But you have to have a helper to watch the scanner while you watch the road, and there is a capture mode that will trap pending and soft codes.

You need vacuum to operate the brake booster and if you dont have the rpm to createenough, the booster wont help. Before starting the car, press down on the brake pedal hard and hold it as you start the car. When the cars starts,you should feel the pedal go down some. That means the booster is working.Are you loosing brake fluid, have to keep adding? Is the booster sucking fluid through the master cylinder's rear seal? Just a few things to check for. If you are introducing the brake fluid into the fuel system, it may be why your 02 sensor triggered a code.