Codes P0442 and P0440 Evap Leaks [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: Codes P0442 and P0440 Evap Leaks

06-20-2010, 10:24 AM
Hey all, just wanted to pick your brains about an issue I've been having. I keep getting returning P0442 and P0440 codes, and have a slight 'ticking' sound coming from the engine exhaust area. It sounds nearly like an exhaust manifold leak, would this throw the Evap codes listed above? Would a faulty EGR or Purge Valve cause an exhaust leak type of sound? I am guessing that the SES light and 'ticking' sound are related, as I always check that the gas cap is tight. I got a new exhaust manifold gasket, as I know GM was notorious for having gasket issues on the Suburbans/Tahoes, but I would rather not dig into that job if I don't have to. Any help would be appreciated. Thanks!

11-18-2010, 04:24 PM
I had the P0442 code come in twice, as in 2 entries. Had the exhaust manifold replaced about 3 years ago, had the gas tank out to change the level sensor, cleaned the throttle body last year and changed the air filter in August. My buddy's code reader spelled out "leak detect: small leak". Anyone ever see this or hear of it?

11-18-2010, 05:48 PM
The leak in question should be in between the vac fitting on the intake manifold and the canister vent solenoid. The hard nylon line is famous for getting cracks in the tighter bends the best way to find the leak is a technician smoke machine

11-21-2010, 07:46 AM
:duh:i had a code P0440, did the smoke test and they found no leaks!!! Manifold gasket was replaced a month ago and we have no leaks....scratch

11-21-2010, 09:35 PM
Sometimes it is just that EVAP vent solenoid is leaking. Its a pretty simple device that is basically a valve that opens and closes, you can test it by removing it and energizing it with 12 volts and blowing though it with your mouth. You should hear it click when its energized and it will plug the vent.

I have seen them either not work at all, or work but not plug the hole, presumably because of dirt, I have even seen the plastic crack visibly and be an obvious source of a leak.

Gas cap not tight or a bad seal when it is tight will cause the same code.

Pretty tuff to find the leak some times without a smoke machine as one other poster already said. Most of the time I get lucky and find the leak with a good inspection of the system, but sometimes not. Look for any gas leaks also, think of the entire tank with the lines and gas cap being an air tight sealed system, any small pin hole will make a "small leak detected" code

11-22-2010, 01:48 PM
Just went into a shop yesterday, and got a P0440 code. The guys at the shop said it could be as simple as a lose gas cap. They said if that doesn't solve the issue, it could also be a fuel filter (I think I have the stock one down there still; 140K miles is alot to have on them).

Could the fuel filter be a cause for poorer fuel economy? Lately I've been getting around 9-11 MPG average, which seems way too low, considering I don't drive with a lead foot (although these would be all city miles, no highway).

11-22-2010, 08:42 PM
I smoke tested it from the shradder valve and the gas cap. NO LEAKS....
light back on again today !!!! I replaced fuel filter a week ago. scratch head

09-12-2011, 10:28 PM
I am having the same problem with my 07 ss, i replaced the evap vent valve and light came right back on...also when i fill up its sometime hesitant to crank up why is this???? can yall help me out :duh:

09-23-2011, 04:13 PM
I am getting the same codes. I replaced the gas cap and now my gas cap light turns on after about 5 miles of driving. Oh, and off topic, my fan seems to run loud at start up, slows down, but never shuts off. Is that normal? Could my fan clutch be going? Hope not, just got the thing a month ago!:undecided

11-29-2011, 12:55 PM
ok can anybody tell me what they did to solve this problem? p0440? inspected under the gas tank and no lines were cracked. I found one line to be bad under the hood so I replaced it. I've had a smoke test done and nothing was found. help!!!!

11-29-2011, 05:47 PM
I gave up on trying to fix it; I decided it may be the the sensor and I will check that out whenever the fuel pump goes out again and I have to drop the fuel tank or just say screw it like I did the low oil pressure warning that nothing seems to fix.

02-13-2013, 03:26 PM
Sorry to bring up an old thread, but this may be of some use to someone. I had a P0440 code. Replaced purge solenoid, vent valve, gas cap, fuel filler neck. Still had code. Since it was winter, and I don't have a smoke machine, I caved and took it to the dealer. They did a smoke test and claimed there was a leak around the fuel pump retainer ring. They drop the tank, then also claim that the fuel pump is corroded.

After both were replaced (to the tune of $911), three days later the SES is back on. Yep, P0440 again. I filled out the online survey that GMC sent me two days later, basically ripping the dealer. The next day the dealer calls and says "I understand you still have the P0440". My wife takes the car in, now we're treated 10 times better. Shuttle service to take her back home while they "spend more time to find out the cause". This time, they claim it is the fuel tank pressure sensor near the filler neck (mounted to the gas tank). He claims that they put their computer on it and drove it around, and the pressure value was moving around. This one was "no charge".

If this doesn't fix it, I'll update this post. But, for those of you stumped by P0440, this may be the cause if you've tried the other suggestions above.

02-25-2013, 02:29 PM
I had a p0440 code and after Smoke test found no leak I checked the purge solenoid and found it was not opening when commanded causing the code to set. I replaced the purge solenoid and it has not come back in almost 2 weeks.

08-20-2013, 03:13 PM
I have the same problem, with a P0440 ODB code. I did all the things to clear it out, but it remains. Is there a specific way to reset the actual light on the dash to make it disappear, or does it automatically go away when the problem is fixed? Is there some procedure I can do to turn it off?

08-22-2013, 11:26 PM
I have the same problem, with a P0440 ODB code. I did all the things to clear it out, but it remains. Is there a specific way to reset the actual light on the dash to make it disappear, or does it automatically go away when the problem is fixed? Is there some procedure I can do to turn it off?
You need a OBD II code reader to clear the error condition. However, if the problem still exists, the code will come back shortly.

It may clear itself after you actually fix the cause and run the car several cycles. Not sure of the number.

08-24-2013, 02:08 AM
I had same code, I cleaned the TB and replaced the EVAP vent solenoid on located on the drivers side mounted on the engine. Very easy to get to and replace. Problem fixed.

There is another one by the gas tank but I did not replace that one.