GM 3800 P1404 & P0404 error code saga
I’ve been wrestling with P0404 “Gas Cap” and P1404 EGR error codes on my 2001 3800-series-II GP-GT for at least a year. Replacing the EGR had no effect, nor did the frequently recommended reset procedures (disconnect EGR, clear code, immediately shut key off, then re-connect EGR). Turns out it was a bad vacuum hose to the evap purge valve! $0.50 of vacuum hose fixed it! Only found this after paying $70 for local GM shop to diagnose and tell me it was the evap valve itself. When I went to pull the vacuum hose off to replace the valve, it crumbled in my hands. It felt like it was burnt.
I went ahead and spent the $25 to replace the evap hose assembly. GM parts man had never seen this before.
So, if you’re seeing the subject codes, check the vacuum lines first. This one looked fine visually, but crumbled as soon as I put the slightest pressure on it.
Reader Comments
After 6 months, this problem has re-appeared. I can reset the codes while the engine is running and drive for at least 45 minutes with no issues. Then when I re-start the car, the codes re-appear.
best thread on the subject:
http://www.obdii.com/ubb/Forum1/HTML/001669.html
Replacing the EGR valve cured both error codes this time. This is an expensive part, but its trivial to replace – anyone can do this themselves. Having a decent code reader has certainly paid for itself.
My local O’Reilly Auto Parts store in Mitchell, IN has been very helpful.