Just thought I'd throw in a comment or two regarding EVAP leak faults and codes. One thing to remember, an EVAP leak code, may not mean there is a leak at all. You also have to take into account HOW the system attempts to determine EVAP system integrity. Cars up to 2006 MY all use the engine and it's manifold vacuum to do the test. That is, the ECM closes off the vent system, then APPLIES manifold vacuum to the tank by opening the CANISTER PURGE VALVE. Then it closes the Purge Valve an sees how long the vacuum takes to trail off. If it looses it quickly, it ASSUMES a big leak; looses it slowly, it ASSUMES small leak. Now, if it NEVER sees the vacuum at all, it ASSUMES what they call a rough leak, and sometimes says "check gas cap". In all cases, the fault is for a leak, but as I said, it may not be a leak at all. I may be a failure of the TESTING MEDIUM, vacuum.

By the same token, a failed vent valve that won't close properly for the test, results in the same thing; a fault for a "leak" because it can't hold vacuum for the test

The code P0455 and P0456 is flagged when the computer detects a leak in the EVAP system. What's the EVAP system? In your fuel tank while you drive the car and move the gasoline around gases form. Now by law this gas cannot be simply released into the atmosphere, so the car uses the EVAP system to store this gas and eventually (when the moment is right) feed them to the engine. The computer monitors that this system doesn't leak, and this code is flagged when the computer sees a problem. The computer has a little pump that creates a vacuum in the system, then with a pressure sensor sees if the vacuum stays. If the vacuum doesn't stay the computer flags this code.

That being said, first culprit is gas cap, next is failing hoses on the charcoal canisters, then close valve, then canister purge valve.

 

Dell, if you look next to where the O2 sensor plugs are, there is a solenoid valve there. If that valve sticks, it will cause the codes that you are seeing. If you pull that valve out and spray it with some carb cleaner, it will remove the gunk that is in it and fix your issue possibly. I had the same problem and after cleaning this valve, all was good.

 

Hi Thermo,
I have the same problem, however, using a cheap ODC2 tool I got a code p1646, which seemed to suggest the 02 heated upstream sensor on bank 1 was faulty. I had a spare so fitted that and had the same code again. Thinking sideways, the ODC also came up with a second answer on the help function that stated: B: Fuel pump relay malfunction (2). I coulden't find a second fuel pump relay and the main was working ok. Then I thought about it and checked the Purge valve and it was faulty and not opening. By disconnecting the clip I tested the terminals and discovered that I was getting around 11.32 volts with the engine on. This triggered another fault code on the ODC which was the P0455 code we expected.
In conclusion, I reckon the gradual loss in mpg happened when the purge valve solenoid went bad so replacing it has put the mpg up to 22 around town. Its worth thinking about this if you get a P1646 code that wont go away.

 

This is the Purge Control Valve, right? Trying to figure out my evap leak and I'm not familiar which which parts are where.

 

dh53, yes, if you look in the engine bay, there is a "hole" to the left of the brake booster. A lot of people use this hole to access the O2 sensor on the back side of the engine. If you go straight in, you should see what would look like 2 canisters about the size of your thumb (each) and some hoses coming in the bottom. It is on a rubber isolator (makes it fun to install, but not that bad). It is the only part in the area other than the plugs for the O2 sensors as I recall.

If you don't mind a little bit of a drive, I live south of you about 2 hours. Granted, I am going to be up in Timonium on Saturday, depending on where you live, may be on my way to/from.

 

Purge valve works like a champ. I put the finger of a rubber glove over the output side then blew on the input side and absolutely no air would pass. Did the same with vacuum and nothing. As soon as I apply 12 v to the pins the air circuit is wide open. I'll look at the canister control valve next. Also watching some Youtube videos on homemade smoke testers, I might try that to leak test the pipes.

Timonium...is there a Jaguar Jamboree at the State Fairgrounds? I really appreciate the offer to help but picking your brain here on the forum is already asking a lot. If I get in a real bind I might throw the tools in the car and tow it south. I thought you were a submariner, did you get lost and end up at an air station?

 

dh53, yes I am a submariner (always under a lot of pressure). Ironically, I am living near an air station (I think they go a little too high, it is affecting their thinking. LMAO, or is it mine now?). I retired from the military 12 years ago and a local placed offered me too much money for a very simple job. So, I moved near the air base (by chance) for this job. I can't argue too much. The area is great and more the pace I wanted once I got out of the military. Got tired of big cities.

As for Timonium, no Jaguar show (I wish). BUt, I am also into model trains and there is a big show there. So, I am going to see that. As for being "too much to ask", bah. You are talking to the guy that ran down to Richmond to help someone install a lift on their truck and when I lived in Norfolk, I rand down to central NC to help a fellow truck member install a dual battery setup. I carry my simple scanner with me all the time to see real time data and if I need to grab my SDD laptop, that is a quick and easy to load in the car. So, if you want me to come over, just say so.