A cracked hose on certain parts of the evap system can be a vacuum leak, or if a valve on the system is sticking open it could maybe cause the same problem Anyway a vacuum leak could cause the car to over compensate for the lean condition and cause a rich condition.

Can an EVAP leak cause engine problems?

Some can involve minor fixes. Some can be massive system failures – especially if you don't fix the situation quickly. An EVAP leak is one of those potential problems that impacts your check engine light.

Can a purge valve cause a P0171 code?

Purge valve seal: If your engine is sounding rough, there could be a large leak causing the P0171 code. You can also check for a bad seal on the purge valve.

Can a EVAP leak cause bad gas mileage?

Decreased Gas Mileage

When a canister purge valve doesn't open as it should, your gas mileage might be negatively affected. The vapors in your car used in combustion will go to the EVAP canister then get vented out into the environment, causing you to use some of the fuel that your car would usually use for burning.

Related Question Can EVAP leak cause lean condition?

How do you test an EVAP system?

Smoke Test – The idea behind the smoke test is simple, blow smoke into the EVAP system and look for smoke escaping from a compromised valve, seal, tube, or hose. Smoke testing is the best way to test the EVAP system. At the same time, it's also either the most expensive or bravest method of doing to.

What does P0457 mean?

P0457 is a diagnostic trouble code (DTC) for "Evaporative Emission Control System Leak Detected". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation.

Will code P0455 cause a lean code as well?

A big vacuum leak will throw a p0455 and cause a lean condition. I would look for a vacuum leak.

What is EVAP gross leak?

During the leak test, the ECM closes the vent control valve to create a sealed EVAP system. If the EVAP system does not maintain the pressure, the ECM recognizes an evaporative emission control leak. In the case of P0455, it is a very large leak. This is usually indicative of a loose, broken, or missing gas cap.

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