Code p0400 and p0440

[griz4718]

I started out with a p0400 (EGR) code. tested components and cleaned egr valve. Best guess was the egr solenoid. Replaced the solenoid and check engine light stayed out for about 4 days. When it came on again it had a code p0440 (EVAP). Changed gas cap to no avail, did this because it was quick and cheap. Could this be just coincidence or are the two codes somehow related? I have a 98 Impreza Outback Sport with 2.2L engine and automatic trans.

 

Thanks in advance.

[color-blind]

First make sure that you installed an oe gas cap, no aftermarket caps allowed. Then look at the charcoal cannister make if you see no obious damage to it then install hose clams on the hoses that attach to it, clear codes and see how it does. Good luck.

[99obw]

Take a look at the gas filler tube for the p0440. Ours was rotted out, I replaced it and the code is gone.

[2X2KOB]

Take a look at the gas filler tube for the p0440. Ours was rotted out, I replaced it and the code is gone.

 

Is that a rubber or metal part that failed? How old was it?

[99obw]

Sorry I didn't explain very well.

 

It's the metal pipe that the gas cap screws into, and it runs down to the gas tank, probably 2'-3' long. It hides behind a black plastic cover in the right rear wheel well. When I removed the cover several pounds of salty sand fell out. It seems that regular washing doesn't clean around this pipe. I also replaced the gas cap, shut valve, and some of the metal evap lines with rubber hose, for a total of around $225. The dealer had all of the parts in stock, which makes me think that this is a common problem. It was original, 99 outback, 198k miles, tons of salt.

 

This is just one possible cause of the P0440, any leak in the system may cause it.

[JHBrooks]

I have the same problem and I was wondering how much was the shut valve?

[rojo]

For folks having problems with the check engine light coming on and turning off, pulling P0400 and P0440 codes (and possibly other emissions codes), here's a tip:

 

Our 1998 Forester was having that problem for a couple of years (2004-2006). The dealer replaced EGR valve, Back Pressure Valve, solenoid valve... to no avail. (Check engine light would return within a few to 500 miles, turn off, come on, turn off...)

 

Finally the dealer mechanic called Subaru tech support, and was advised of a tech tip dated June 2006 about P0400 EGR code. He followed the procedure in the tech tip, and found that the hose connected to the MAP sensor was pulled loose at a "T" in the vaccum line. (MAP = Manifold Absolute Pressure.) Reconnected line. Voila!

 

This hose had apparently jiggled loose (or been disconnected?) during a clutch job 2 years earlier. This "T" in the vaccuum line is apparently obscured from sight when everything else under the hood is in place. Don't know how hard it is to access.

 

Just read in Wikipedia that the MAP sensor provides data "used to calculate air density and determine the engine's air mass flow rate, which in turn determines the required fuel metering for optimum combustion." And, "The MAP sensor can also be used in OBD II (on-board diagnostics) applications to test the EGR (exhaust gas recirculation) valve for functionality." Thus the connection between the EGR code and this disconnected hose.