Hi I own 2018 traverse high country and I have a big problem I don’t know how to solve I have the codes P0420,P0442,P0446,P0496 … I bought a used charcoal canister and its added the code P0449 when I return the old vent solenoid to the new charcoal its return to only 4 codes
I replaced the purge valve twice and it get bad within days
And now the car is unstable especially after brake and I feel it can’t go fast easily
P0420 means the computer thinks the cat isn’t working correctly. It makes that determination based on the relationship between the pre- and post-cat O2 sensor output signals vs time. Before replacing the cat, ask you shop to use their pro-level scan tool to inspect those signals and their relationship. The problem could be a faulty o2 sensor or sensor wiring, rather than the cat. (But if I had to guess, it is probably a faulty cat.)
As for the evap problems, explain why you replaced the canister. Usually that wouldn’t have to be replaced unless it got flooded with gasoline due to a fault with a fuel tank valve. Is that what happened? If the canister got flooded with gasoline, all of the evap valves are probably malfunctioning, caused by charcoal grit getting into the various evap hoses. They’ll continue to fail even if you install a brand new canister until all the hoses are either replaced or cleaned of all the carbon grit.
The small leak symptom is saying the computer is closing both the vent and purge valve for a pressure (or vacuuum) test the entire evap system. The system should hold pressure for a certain amount of time. In your case it isn’t. If the vent or purge valve is carbon clogged, that can prevent it from fully closing, and will cause a small evap code.
Thank you I will check the hoses tomorrow … I replaced the entire canister cuz it has a crack and I thought it’s the main reason for these faults but even with the new one the faults remains
This sort of problem may require a shop to use a smoke test to discover the actual problem. They’ll quickly be able to check the integrity of the main evap tube running from tank towards engine then to canister, the purge valve tube, the vent valve tube, the misc. tubes attached to fuel tank, & fuel cap seal.
If the catalytic converter actually failed, it’s covered my the manufacturer for 8 years/80,000 miles under the emissions warranty.
If your catalytic converter failed: If your catalytic converter broke down and your vehicle is under warranty, you may not need to pay to have it repaired or replaced. The Environmental Protection Agency mandates that automakers provide special warranties for emissions components, including catalytic converters. Under these warranties, major emissions components are covered for eight years or 80,000 miles, whichever happens first.
Tester