XJ Failed Emissions Test

2001 XJ (58,000 miles) failed and has codes P0442 (small leak) and P0455 (large leak) in the evaporative emissions system. Other than the gas cap, does anyone have any ideas what to look for first? Thanks.
Reply to
kokonutty
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P0442 OBD-II Trouble Code Technical Description Evaporative Emission Control System Leak Detected (small leak) What does that mean? This indicates a fuel vapor leak in the EVAP control system. It means a very small leak has been detected. In fact, the leak can be from a hole as small as 0.04" in diameter. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine. Symptoms You likely won't notice any drivability problems. Causes A code P0442 most likely means one or more of the following has happened: . A loose or improperly affixed gas cap . A non-conforming gas cap (i.e. not factory/original brand) . A small leak/hole in a fuel vapor hose/tube . Other small leak in EVAP system . Faulty vent o-ring seal Possible Solutions With a P0442, the most common repair is to: . Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back. . Otherwise, replace the gas cap, or . Inspect the EVAP system for cuts/holes in tubes/hoses

P0455 OBD-II Trouble Code Technical Description Evaporative Emission Control System Leak Detected (no purge flow or large leak) What does that mean? This indicates a fuel vapor leak or lack of purge flow in the EVAP control system. It means a large leak has been detected. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine. Symptoms You likely won't notice any drivability problems. Causes A code p0455 most likely means one or more of the following has happened: . A loose or improperly affixed gas cap . A non-conforming gas cap (i.e. not factory/original brand) . Other leak or damaged piece in EVAP system Possible Solutions With a p0455, the most common repair is to: . Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back. . Otherwise, replace the gas cap, and/or . Inspect the EVAP system for cuts/holes in tubes/hoses (you may hear a vacuum noise or smell fuel), repair if necessary

Reply to
billy ray

Reply to
L.W.(Bill) Hughes III

Thanks for the fast replies guys...pretty much what I thought, but I was hoping someone might point me beyond the gas cap to where they may have seen specific problems in the past. The info BH III posted including the TSB is for Grands, not XJ's but DCP valve could be the source, I guess but it doesn't seem easy to get at right away on the Grand and no idea wher it is on the XJ.

Reply to
kokonutty

Reply to
L.W.(Bill) Hughes III

If it turns out not to be the gas cap my "P0442" was a minute crack in a hose. Couldn't find it. The dealer (mine at least) has a smoke generator that will spot the leak.

Reply to
FranK_v7.0

When I had the P0456 error code this was the cause:

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Reply to
billy ray

Reply to
L.W.(Bill) Hughes III

The gas cap is by far the most likely cause of your problems. By far.

They can test the cap to see if it holds pressure, I don't get why this would cause a failure at the smog station. If the cap is bad, they are happy to sell you a new one for more than double the "street price" and reset the code and move on.

Reply to
Jeff Strickland

Have you ELIMINATED the gas cap yet?

The gas cap is common to both codes, and is by a wide margin the most likely source of the codes you got. You MUST eliminate the gas cap as the source before you go any deeper, or you will be wasting both time and money. If you went out and bought a locking gas cap to keep shitheads from stealing your gas, then the cap is the cuplrit. I've been told by at least two smog testers that locking gas caps frequently fail the pressure test that they put the caps through.

Reply to
Jeff Strickland

I'm not sure I'd be quite that strong. It _could_ be another problem, but he won't know for sure until he makes sure the gas cap is not the fault. Given

100 chances for failure, the odds are good that at least 95 come from the cap, the other 5 come from a cracked hose. Since we're discussing an '01, I'd take bets that the hoses are in good condition.

Reply to
Jeff Strickland

Nope, new gas cap $12.99.

Reply to
billy ray

I had that, a small crack in a plastic fitting that ran to the intake manifold, duct tape fixed it.

Troy

Reply to
Troy

Sure. Twenty dollars of cleaner for a fifteen dollar cap. Plus the new one can help with the occasional gas fume smell. The canister now is a bitch to get at.

L.W.(Bill) Hughes III proclaimed:

Reply to
Lon

Reply to
L.W.(Bill) Hughes III

Thanks for all the replies and, as my first message stated, I was looking for things to look for if I checked out the gas cap and needed to go beyond there. I was trying to have Plan B, C, etc. in mind before starting. Turns out even that was more than I needed. I disconnected the battery to reset the codes and got none after making sure the gas cap was tight. After a few days and a number of trips the light is still out. That "problem" is over for now.

This place had been recommended to me as a place that is liberal in getting cars to pass, but they didn't even reset the codes and check out the cap and kind of waffled when I asked about the cap so I'm not going back there. I know my brakes are not that great but now I'm also questioning whether I need the rotors replaced now as they said or I can go a while first. I was reading the newspaper in the office when they pulled the wheel and "determined" I needed replacements but they didn't call me in to show me. So I need to get reinspected in the next two days and if I need brakes, I'll take a look and get them (original rotors, pads at 40K, sometimes drive a bayside road that floods at high tide - salt water) but I'm not giving the business to the "recommended" guy...screw 'em. Thanks again.

Reply to
kokonutty

Need to replace rotors is a "yes" or "no" question, there is nothing subjective about it. If they do not meet the required thickness specification, they are junk. At least, that is what the law says.

Earle

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Reply to
Earle Horton

Earle,

I think his concern is whether this garage wanted to just replace his rotors to pad the bill rather than should he machine them to an illegal depth.

I base this on his comment that they did not check his gas cap (which turned out to be the cause of the codes) and 'waffled' about that being a possibility....

Reply to
billy ray

That begs the question, why didn't the smog station do that for you? All he had to do is pressure test the cap, which is a standard part of our smog checks in California.

The way to find out if you need brakes and rotors now or later is to look at them now, or wait for later when the make noise.

HINT It's best to do them before they make noise.

Reply to
Jeff Strickland

Okay, so the light came on again after a couiple of days so I replaced the gas cap and the station cleared the codes, I put on 150 miles to get the computer "ready" and the Jeep passed the emissions test. (The brakes passed the safety test as is).

Three weeks later the "check engine" light is back. Assuming I get the same codes this time (0442 and 0455-small and large leaks) where is a logical place to find a probably intermittent evaporations system leak? With a specific target, I may try to find it now, otherwise, I'll just wait until I need the emissions test again next year.

Reply to
kokonutty

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