This is a discussion on 2013 WRX P0451 Code Evap Emission Control System within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Originally Posted by Cho.co.Pie Are all your cars stock or modified? I just hit 9k miles on my '13 wrx ...
Just another update from me. Turns out my code was somehow read wrong (wtf autozone) and they saw the P0451 from before my wiring harness ground(s) were re-soldered etc. Turns out my code was a P0455 from my gas cap being faulty. I am now over ~400 miles give or take with no CEL P0451 related issues since the re-soldering. Was also reassured that 3/4 cars that had the P0451 that came into the dealer and got the same fix as my car, the techs have not seen them again for the same issue since.
You guys that are struggling still, ask about the ground wire(s) etc. I'm pretty confident now that that is the problem!
Just realized I forgot to update this thread. The dealership replaced the entire wiring harness on October 2nd. I dropped it off in the morning, they had it done by the afternoon. No check engine lights since and everything appears to be running correctly.
I finally have an update as well! I took the car in a couple of weeks ago to get the codes looked at for the third time, but this time they checked the wiring harness. I took it in on a Thursday to get the initial testing done, then they said they would need it overnight, so I scheduled to bring it in the following Monday so I could get a rental.
Here’s the text from the initial service report on Thursday:
“NECESSARY TO REMOVE THE ENGINE HARNESS AND INSPECT FOR SHORT.
ISSUE IN HARNESS TO MAP SENSOR.”
Here’s the text on the report that I got when I picked up the car today:
“P0451 EXCESSIVE RESISTANCE IN B21 CONNECTOR CAUSING FAULT TO
SET. P0301-P0304 AS WELL.
REMOVED INTAKE AND REPLACED ENGINE HARNESS AS NECESSARY.”
For reference, the part number for the harness is listed as 24020AF070.