Brake pedal is hard when engine running in low gear or out of gear. Changed vacuum pump, hasn't fixed problem. (Although pump was 2nd hand part so can't be 100% sure that isn't faulty). Also the red engine light comes on sometimes and car goes in limp mode. Goes OK after turning engine off. Could these two problems be connected in any way by a vacuum leak in a hose? Or is it just two separate problems? Car is a 1.8 tdci.