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2007 Jeep Wrangler P0440 Code Reappears After New Gas Cap Installation

Model: 2007 jeep wrangler Fault Code: P0440 Posted: 2012-04-30 17:48

Hello, I own a 2007 Jeep Wrangler Unlimited. A week ago, I received the P0440 diagnostic code, which indicates an evaporative emission system leak. After researching online, I replaced the gas cap, cleared the code, and waited two days—however, the P0440 code returned and is now showing up twice in my OBD2 scanner (1/2 and 2/2). I inspected all fuel lines and hoses, and they appear to be in good condition. The vehicle has 33,500 miles on it since new. I'm concerned about taking it to a dealership, as the emissions warranty only covers issues related to the catalytic converter or evaporative control module (ECM). I've only used this Jeep off-road once and have very low mileage. Can anyone provide guidance? Would greatly appreciate any advice.

Related fault codes
P0440
Comments (6)
Anonymous 2012-04-30 18:58

The most likely causes are a faulty leak detection pump or an issue with the EVAP system sensor (Esim switch), depending on your Jeep's specific model configuration.

Anonymous 2012-05-02 22:28

I visited a dealership and purchased a Mopar gas cap. The aftermarket cap displayed a gas cap error on the scanner, so I switched to an original Mopar cap. After installation, I drove 80 miles with no issues. How long does it typically take before the vehicle is ready for smog testing? Is around 80–100 miles sufficient to complete the EVAP system cycle and get all systems back online?

Anonymous 2012-05-03 04:58

Normally, the system completes its self-test within 80 miles. However, a quick check of the monitor status using an OBD2 scanner or advanced code reader will confirm whether the EVAP system has completed its monitoring cycle.

Anonymous 2012-05-10 20:37

Okay, thanks. I actually took it to a dealership for the P0440 issue. They spent all day on it and performed a smoke test—no leaks were detected. They concluded that the problem was a loose gas cap and reset the computer. I’ve already installed a new cap and tightened it securely. However, just one day later, the P0440 code returned, and the EVAP system is still not ready. As a result, I failed my smog test. Now I'm over $300 in expenses and back to square one. I’m planning to order a purge valve, leak detection pump, and canister—does that sound like the right course of action?

Anonymous 2012-05-10 22:15

It seems you may have accidentally added periods after every word—this could affect readability and clarity in written posts.

Anonymous 2012-05-14 22:14

I don’t know why, my iPad automatically adds periods after each word when I type. It’s a formatting issue on the device itself.