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2020 Ram 1500 Laramie - P0456 Small EVAP Leak Code

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Mark S. · rep 0 · May 22, 5:39 AM · 1 replies · solved · Question

Vehicle: 2020 Dodge Ram 1500 Laramie

Hey everyone,

My Check Engine Light came on yesterday in my 2020 Dodge Ram 1500 Laramie. I hooked up my OBD-II scanner and it's throwing a P0456 code, which indicates a "Small EVAP Leak Detected."

The truck seems to be running fine, no noticeable changes in performance or fuel economy. I checked the gas cap, tightened it, and even removed it and put it back on a couple of times, but the light is still on.

Has anyone else experienced this with their Ram? What are the common culprits for this code on these trucks? Any advice on what I should check next before taking it to a shop?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:39 AM

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Hello John,

The P0456 code, "Evaporative Emission System Leak Detected (Small Leak)," is a common issue and often doesn't indicate a severe problem, but it does need attention to clear the Check Engine Light and ensure your emissions system is functioning correctly.

Here are the most common causes and steps you can take:

  1. Gas Cap: While you've checked it, sometimes the seal on the gas cap itself can degrade over time. Ensure it's the correct cap for your vehicle and that it clicks several times when tightened. If it's old, consider replacing it with an OEM cap.
  2. EVAP Hoses: Inspect all visible EVAP hoses for cracks, disconnections, or damage. These hoses run from the fuel tank to the charcoal canister and then to the engine. Look for any signs of wear or loose connections, especially around the purge valve and vent valve.
  3. EVAP Purge Valve: This valve is typically located on the engine and controls the flow of fuel vapors from the canister to the engine. A faulty purge valve can stick open or closed, causing a leak. You can often test it with a vacuum pump or by listening for a click when the engine is running.
  4. EVAP Vent Valve/Solenoid: Located near the charcoal canister (often near the fuel tank), this valve opens to allow fresh air into the EVAP system. If it's stuck open or has a crack, it can cause a small leak. Visually inspect it for damage.
  5. Charcoal Canister: Less common for a small leak, but a damaged canister could also be a source.

When to See a Shop:

If after checking the gas cap and visible hoses you're still getting the code, it's best to take your Ram to a qualified technician. They have specialized smoke machines that can inject smoke into the EVAP system to visually pinpoint even the smallest leaks, which is the most effective way to diagnose a P0456 code accurately. They can also perform more in-depth electrical tests on the purge and vent valves.

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