QuestionI have 1996 corolla 1.6l with code P0401, EGR incorrect flow detected, I use vacuum pump to test EGR valve, it’s working beautiful, I checked all the vacuum hose routing folow vacuum diagram, no problem found, I replaced VSV for EGR and cleared the code. Next day, the car came back with same code, I replaced used modulator, it came back with same code again. Now I have no idea what to do next
AnswerOK, so when you put vacuum to the EGR valve it kills the engine is this correct?
Have you checked the throttle body vacuum fittings to see if there is vacuum from both the P and R ports when revving the engine, if not the ports are clogged and need to be cleaned out, if that's ok too see if the EGR temp sensor is connected( calif spec only). Although rare, the temp sensor may be the problem.
