Last Sunday we changed the EGR valve (Duralast brand) and the next day the SES light came back on. Checked the car today (Actron scanner) and it has two codes...
P0305 - Misfire detected cylinder 5
P0401 - EGR system performance...
We cleared the codes and test drove it to find out what code is setting first. On a hard pull or under high load the P0305 sets first. It took two runs to get that code by itself, on the first run both codes set at the same time. We checked the plug and swapped wires between #1 and #5. P0305 set again by itself. So now we got P0305 to set twice by itself under a high load.
Ran out of time to swap the coils and try again. My question is what gives? or why is it setting both codes?
I am thinking that OBD cannot run the EGR test with the P0305 code stored so it sets the P0401 when it cannot run the test. So, I advised my dad to lay off and keep it below 2500 RPM. Basically, lay off until it runs the EGR test. The scanner displays I/M monitors and for EGR sytem the status is "Not ready" or test not completed.
TIA
UPDATE - missfire and EGR fault are now fixed! The missfire was a cracked spark plug. The EGR fault got worse and we found a plugged EGR port in the upper intake manifold. used a tube cleaner and hammer (tapping around the outside to break up the carbon). A couple of hours later it was clear as can be and it passed the OBD test soon after.
