I received my first Service Engine Soon (SES) light in a long time yesterday. As a result, I did alot of research on the topic and thought I'd share what I did to resolve the issue as the information online related to the G37's EVAP system is somewhat fragmented.

First off, when I scanned for codes, the following one came up: P0441 (P0441) Evaporative Emission System Incorrect Purge Flow (see pic below):



This indicates a problem with the Evaporative Emission Control (EVAP) System.

If you were not already aware, the EVAP System is responsible for capturing fuel vapors produced in the vehicle's fuel system, storing them in a charcoal canister, and safely burning them off in the engine.

There is a nice write up here which describes the function of each component in the EVAP system if you're interested: https://www.autolinepro.com/blogs/ho...ap-system-work

The main components to troubleshoot on our cars include:

1.
Gas Cap: https://www.z1motorsports.com/fuel-p...3-p-10422.html (Z1 lists the PN)
According to the Service Writer/Parts Guys I spoke to at Infiniti, a bad gas cap is the issue 70% of the time when a P0441 code is thrown. If you take the cap off and it looks somewhat crusty around the seal like mine did (see picture below), then replace. This is a stocked item at the dealer and mine always gives me a 15% discount if I ask.



2.
EVAP Canister Vent Control (Purge) Valve: https://www.z1motorsports.com/intake...e-p-14993.html (Z1 lists the PN). This device is located in the rear of the car near the gas tank. I was told by both gentleman at Infiniti that this was the second most likely item to fail within the EVAP system and cause the P0441 code to be thrown. This is a stocked item at the dealer and I was originally planning to replace.

The EVAP Canister Vent Control (Purge) Valve connects to the EVAP Canister (charcoal) as described here: https://www.myg37.com/forums/engine-...37s-coupe.html

This video does a good job of showing how to test/replace the EVAP Canister Vent Control (Purge) Valve:


3.
EVAP Purge Solenoid: https://www.z1motorsports.com/intake...d-p-11312.html
This device is located at the top rear of the engine, just below the engine cover (needs to be removed to access - more here: https://www.myg37.com/forums/intake-...-location.html). The guy at the parts counter said that these rarely fail and the last one they ordered was over 5 years ago (items 1 and 2 above are ordered more frequently). Not a stocked item, and fairly straight forward to replace.

Note that there are two hoses coming off the purge solenoid. One side contains a hose that comes up from the gas tank and contains the port with a screw on cap that's used for "Smoke Testing" to check for leaks in the EVAP systems (https://www.autolinepro.com/blogs/ho...for-evap-leaks) and the hose on the other side goes to the intake manifold.

The video here shows how to go about testing the EVAP Purge Solenoid:


Note that it takes a long time to warm up and activate this solenoid (I had to drive around town for 20 mins). Be patient.

But prior to finding that video, I saw this one, showing the hose going from the EVAP Purge Solenoid to the manifold (PN 14912-EY01B - Hose Fuel Evaporation) Control):


I decided to check mine and also test item 3, thinking at this point that the problem had to be with items 1 or 2.

I was wrong, the hose going from the EVAP Purge Solenoid to the manifold (PN 14912-EY01B) was destroyed in a similar manner (see the pic below) to the one in the video above. The other side going back to the canister still looked new. Odd. Perhaps because the hose going to the manifold is closer to the engine it wears alot faster? Not sure. Also note that with the hose removed, and once the solenoid activates, it will eventual turn the car off if you do not replace the hose.



So I called the dealer back to order the $30 "Hose Fuel Evaporation Control" replacement hose. Not in stock -> next Friday they could have it.

Wanting to resolve the issue now, I went to AutoZone to find a similar size piece of 11/32nds hose. Bingo, for $3 they sold me a foot of Crankcase Ventilator hose that I cut to 6.5" and it fit perfectly (see pic below, used original spring clamps - disconnect the solenoid connector if you need more room) Cleared all codes and drove around with the new gas cap and hose, no more SES light/P0441 error code.



Finished product. I also spent 15 mins or so cleaning and checking for cracks/damage many of the other hoses I could access with the engine cover off.


Hope someone else finds this useful when troubleshooting the same code.