I have a 2004 jeep Cherokee 6 cylinder with the check engine light on. the codes indicate the gas cap or evap canister leak. How can I check or get to the evap canister?

Replace gas cap. The check ENGINE light is a warning indicator.

Possible causes - Missing or loose fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- EVAP canister or fuel tank leaks
- EVAP system hose leaking
- Fuel tank leaking The P0455 it's a very common code, because the code is set if the gas cap is loose or missing. Start by tighten the gas cap and clearing the code. In most cases the code can be clear by disconnecting the car battery for about 30 minutes.

When is the code detected? EVAP control system has a very large leak such as fuel filler cap fell off, EVAP control system does not operate properly. Possible symptoms - Engine Light ON (or Service Engine Soon Warning Light)
- Possible a noticeable fuel odor caused by the release of fuel vapors P0455 Buick Description This diagnosis detects leaks in the Evaporative Emission System (EVAP) purge line using engine intake manifold vacuum. If pressure does not increase, the Engine Control Module (ECM) will check for leaks in the line between the fuel tank and EVAP canister purge volume control solenoid valve under the following vacuum test condition. The vacuum cut valve bypass valve is opened to clear the line between the fuel tank and the EVAP canister purge volume control solenoid valve. The EVAP canister vent control valve will then be closed to shut the EVAP purge line off. The EVAP canister purge volume control solenoid valve is opened to depressurize the EVAP purge line using intake manifold vacuum. After this depressurization is implemented, the EVAP canister purge volume control solenoid valve will be closed.
if tightening the cap or replacing the cap does not help take your car to a shop to have it diagnosed as it requires special tools/equipment to test this and get an accurate results to find what needs replacing.

OBD code P0442 Small EVAP leak detected you may need to check the EVAP canister under the vehicle and the purge valve as well check for cracks on the canister or the purge valve and check all the rubber hoses connected to them foe cracks or holes. If you find any damage parts replace them. P0455 which means a large EVAP leak is sometimes referred as the gas cap leak check your gas cap and secure it tight if you still have the code change the gas cap hope this helps after you find and fix the problems get the vehicle to a shop and they will use an OBD scan tool to clear the codes.

P1495 indicates a Leak Detection Pump Solenoid Circuit error. The Leak Detection system is located under the hood on the driver's side inner fender. The solenoid is located under or behind the leak detection pump. This system works in conjunction with the EVAP system, and one of the most common error causes is a loose or non-airtight gas cap. Try tightening or replacing your gas cap and see if the code disappears after a normal driving cycle (about 50 miles). Good luck.

Usually this P0456 code is caused by an incorrect or faulty gas cap. Filling the fuel tank with the engine running could conceivable cause this code as well or if the cap wasn't properly tightened. Any of the following could also be the cause:

• A small leak in any of the EVAP hoses or fuel tank hoses
• A small leak in the purge valve or vent valve
• The EVAP Canister may be leaking

Small emission leak would indicate to me that the exhaust is leaking, maybe, throwing off the O2 sensor.

If it's an evaporative leak, then I would make sure the gas cap is on tight, and that the filler tube is connected with a vapor tight connection to the tank, and that the tank has no leaks in it.

What was the code, exactly, if I might ask?

P0455 indicates a large leak in your Evaporation emissions system. This system stores fuel vapor from the fuel tank in a charcoal canister where it is later purged and burned in the engine.

The most obvious cause for this would be a loose gas cap. If the cap is tight then you can carefully inspect all of the evap hoses for cracks. It is very common for these to crack and leak on all chrysler products.

If you don't see anything obvious than your next step is to have the evap system smoke checked for leaks. The smoke will be introduced into the evap system under slight pressure. Wherever the smoke comes out is the source of the leak.

If no leaks are found than the usual suspect is the NVLD (Natural Vacuum Leak Detection) pump. Another common failure on chrysler products.

Hope that helps!

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

I would start with the gas cap replacement and see if the issue resolves itself. If you do have a problem with the EVAP (canister) system, it may require tools the average person does not have to help diagnose and correct/repair.

P0440:

Remove and reinstall the gas cap, clear the code, and drive for a day and see if the codes come back.

Inspect the EVAP system for cuts/holes in tubes/hoses

Inspect for damaged or disconnected hoses around the Evap purge solenoid

Check and/or replace the sensor

Check and/or replace the purge valve

Have a professional use a smoke machine to detect leaks

P0441:
Bad vacuum switch

• Broken or damaged EVAP line or canister
• Open in PCM purge command circuit
• Open or short in Voltage feed circuit to Purge Solenoid
• Faulty purge solenoid
• Restriction in EVAP solenoid, line or canister
• Corrosion or resistance in purge connector
• Bad PCM

What is the exact code?
The evap canister captures and burns fumes coming from the gastank.
If it is saturated with fuel 9from topping off) it can lead to vapor lock.
Please reply with the code number ( ex P01142 )

Thanks