S
Surfwax
Guest
Corolla? I'm trying to test the fuel pressure b/c I'm getting a check engine light with DTC PO171. Before having the O2 sensor(s) replaced, I'm trying to do everything I can on my own to find out the issue. I've already cleaned the mass air flow sensor and want to check my fuel pressure next to see if I should look into the fuel pump or fuel filter. I have a scantool, so I can perform some tests through the OBDII connector if there is a way to isolate the issue this way. Any help will be much appreciated! Thanks.