My 2006 XJR with 165500 miles previously got this code and the dash said check fuel filler cap. Code would trigger at about 3/4 tank, never when filled. I did not see any cracking in the gas cap seals, but I replaced the cap anyway. I also added seafoam fuel system cleaner. Problem went away for three to four months, but has started again during a recent cool spell (temp in upper thirties in the morning almost 60 degrees F in the afternoon)

Message where the mileage normally displayed says check fuel cap. Fuel is 3/4 tank.

Any thoughts on what to look for? I looked for any loose connectors for evaporative system under hood.

 

This is from the manual and would be the steps I'd take.

PINPOINT TEST G307413p2 : DTC P0442, P0444, P0445, P0455, P0456; LEAK DETECTED: LARGE/20 THOU/40 THOU, PURGE VALVE CIRCUIT MALFUNCTION, OPEN/SHORT CIRCUIT,

G307413t3 : CHECK FUEL FILLER CAP FITMENT AND CONDITION OF CANISTER, PIPES AND CONNECTORS

1. Make sure that the fuel filler cap is correctly installed and tightened. 2. Check the condition of the carbon canister. 3. Check the condition of all accessible pipes and connectors in the vapor line.

Are the canister and all pipes and connectors in good condition? -> Yes

GO to Pinpoint Test G307413t4.

-> No

REPAIR as necessary. CLEAR the DTC. Carry out a full evaporative system monitor drive cycle. Recheck DTCs. For additional information, see "diagnostic drive cycles" above.

G307413t4 : CHECK THE CANISTER PURGE VALVE DRIVE CIRCUIT FOR HIGH RESISTANCE

1. Disconnect the battery negative terminal. 2. Disconnect the canister purge valve electrical connector, EC63. 3. Disconnect the ECM electrical connector, PI01. 4. Measure the resistance between EC63, pin 02 (UY) and PI01, pin 66 (UY).

Is the resistance greater than 5 ohms?

-> Yes

REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. CLEAR the DTC. Carry out a full evaporative system monitor drive cycle.

-> No

GO to Pinpoint Test G307413t5.

G307413t5 : CHECK THE CANISTER PURGE VALVE DRIVE CIRCUIT FOR SHORT TO HIGH VOLTAGE

1. Reconnect the battery negative terminal. 2. Turn the ignition switch to the ON position. 3. Measure the voltage between EC63, pin 02 (UY) and GROUND.

Is the voltage greater than 3 volts?

-> Yes

REPAIR the short circuit. For additional information, refer to the wiring diagrams. CLEAR the DTC. Carry out a full evaporative system monitor drive cycle.

-> No

GO to Pinpoint Test G307413t6.

G307413t6 : CHECK THE CANISTER PURGE VALVE DRIVE CIRCUIT FOR SHORT TO GROUND

1. Turn the ignition switch to the OFF position. 2. Measure the resistance between EC63, pin 02 (UY) and GROUND.

Is the resistance less than 10,000 ohms?

-> Yes

REPAIR the short circuit. For additional information, refer to the wiring diagrams. CLEAR the DTC. Carry out a full evaporative system monitor drive cycle.

-> No

GO to Pinpoint Test G307413t7.

G307413t7 : CHECK THE CANISTER PURGE VALVE POWER SUPPLY

1. Turn the ignition switch to the ON position.
Make sure the EMS relay is energized. 2. Measure the voltage between EC63, pin 01 (GU) and

GROUND.

Is the voltage less than 10 volts?

-> Yes

REPAIR the circuit between the canister purge valve and battery. This circuit includes the front power distribution box, fuse 14, the EMS relay, and the high power protection module. For additional information, refer to the wiring diagrams. CLEAR the DTC. Carry out a full evaporative system monitor drive cycle.

-> No

INSTALL a new canister purge valve.
Evaporative Emission Canister Purge Valve - VIN Range: G00442->G45703 (17.15.30) Carry out a full evaporative system monitor drive cycle. Recheck DTCs. For additional information, see "diagnostic drive cycles" above.

 

A little more info. Probably should have posted this first, sorry.

 

I decided to top off the gas tank. I found that the retainer attaching the cap to the fuel filler opening was pinched between the cap seal and the filler neck. I did not realize that the retainer was long enough to do that. By the time I got home to take the attached photos, The indent in the seal had gone back to normal.

 

Here are the photos that should have attached to the last post. I don't care for the format change. It was easier to share photos before.

 

I have been using this forum for several years, but after this last format change, I can't get attachments to post.

 

OK but you issue is resolved? Makes sense since the first time was the cap too. Glad it worked out.

 

Sean W;

I will let you know after burning off a quarter tank whether the issue returned.

 

Here's to hoping and wouldn't it be great if every repair worked out like that?

 

Mike, did you resolve this?

 

I am now just under 1/2 tank at about 3/8. No code. So in my case, the cap retainer getting caught between the cap and filler neck was in fact the culprit. So, always check that first.