My check engine light came on in my 2003 Dodge Ram 1500 4x4 5.7L. I had it checked, and I'm told it's a leak in the emissions, apparently very small. I changed the gas cap, had the light turned off, but within a day it came back on. Any help?

P0442- Evap Emission Ctrl Sys Leak Detected (smallleak)
You have a small leak in the emission sys. You can do a smoke test on the vacuum sys and see where the smoke is pulled in and that is the leak,

Small leak in evaporative emissions system. Basically takes fuel vapors and recirculates them back to engine to be burned rather than vented into the atmosphere.One common cause of light on dash is faulty/dirty gas cap seal. Did you add fuel just before light came on? Otherwise a small leak at a hose etc., in system, as well as faulty purge system may also cause it.

this code# po442 is avery small leak in the evaporative emission control system. First check that the gas cap is on tight, past the clicking sound. this uaually solves the problem. if you need more help get back to me and we'll go from there. Please rate my fix as i strive to be the best Thanks Ray

po442 is evap emission control system leak (small) 1 of the lines for emissions is leaking. po455 is-- emission control system leak (large). turn off light with code scanner after it is fixed.

small leak detected needs to have a smoke machine hooked up. The leak is very small and undetectable to the eye or ear. Before you spend the money for the test, (and the repair is usually cheap) make sure your gas cap is tight and that the seal has no breaks. The most comon cause of "small leak detected" is the gas cap.

The leak in your evap system is very small at .020. It is more than likely a small split in a hose somewhere. The cap is probably ok, we rarely find a bad one. If it is a small split in a hose it will only get larger over time. Here is the factory info on the code. We have found that alot of these leaks are from a small hose on the evap canister under the vehicle, but with out looking at your vehicle it is hard to say. If the leak goes away or is no longer large enough to be detected, your light will go out after a few days. These leaks are emmissions related and will not effect the integrity of the vehicle. I would have it checked and corrected if the light stays on at your convienience.

Symptom List:
P0442-EVAP LEAK MONITOR MEDIUM (0.040) LEAK DETECTED
P0455-EVAP LEAK MONITOR LARGE LEAK DETECTED
P0456-EVAP LEAK MONITOR SMALL (.020) LEAK DETECTED
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P0442-EVAP LEAK MONITOR
MEDIUM (0.040) LEAK DETECTED.
When Monitored and Set Condition:
P0442-EVAP LEAK MONITOR MEDIUM (0.040) LEAK DETECTED
When Monitored: Immediately after a cold start, with battery/ambient temperature
between 40° F and 90° F and coolant temperature within 10° F of battery/ambient.
Set Condition: If there is a leak larger than 0.0409 and smaller than 0.0809 in the
evaporative system.
P0455-EVAP LEAK MONITOR LARGE LEAK DETECTED
When Monitored: Immediately after a cold start, with battery/ambient temperature
between 40° F and 90° F and coolant temperature within 10° F of battery/ambient.
Set Condition: There is a leak larger than 0.0809 in the evaporative system.
P0456-EVAP LEAK MONITOR SMALL (.020) LEAK DETECTED
When Monitored: Immediately after a cold start, with battery/ambient temperature
between 40° F and 90° F and coolant temperature within 10° F of battery/ambient.
Set Condition: There is a leak larger than 0.0209 and smaller than 0.0409 in the
evaporative system.
POSSIBLE CAUSES
LEAK AT GAS CAP
VEHICLE HISTORY AND SERVICE BULLETIN INVESTIGATION
VISUAL AND PHYSICAL INSPECTION
VERIFY EVAPORATIVE EMISSION SYSTEM LEAK
EVAP PURGE SOLENOID OPERATION
INTERMITTENT LDP MONITOR FAILURE
EVAPORATIVE EMISSION LEAK DETECTION
GAS CAP
LDP COMPONENT LEAK

"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."
Hope that helps..

P0456 = EVAP Emissions Control System Leak Very Small

Is the gas cap on tight or is the seal damaged? If it needs replacement, get it from the dealer.

Hello, I have a 2003 Dodge Ram 6 cylinder ( Ram Pick -up 1500) The indicator lights are coming on. One says LAMP OUT, and the other is a picture of the engine. I have no idea. Doesn't seem like anything is wrong with the engine and I didn't find any lights that where out. I need help.


Mr. Brian C. Daniels

Please email me back at [email protected]

P0442--Evap Emission Sys. leak detected small leak
P0455--Evap Emission sys. leak detected gross leak
P0456--Evap Emission Sys. leak detected very small leak