Hi everyone,
I have a 2014 Santa Fe Sport with the 2.4L engine. It only has 80k miles, but the engine was replaced under warranty at 65k miles due to excessive oil consumption. The only engine-related modification is a K&N cold air intake.
Last spring, a few months after the engine replacement, my CEL came on. The code was P0420. I cleared it and it came back the next day. This happened 2 more times in the same week. I ended up pulling out both O2 sensors and cleaning them with carb-cleaner. They had a bit of carbon built up on them, but I cleaned it all off and reinstalled them. This fixed the issue until tonight.
Tonight, I noticed my CEL was on again. In addition, I've noticed a huge drop in gas mileage. My trip meter usually says I'm getting 24-28 mpg, but now it says I'm only getting 17, which is much lower than it should be. I cleared the code again and will see if it comes back. I'm sure it will come back though, and I’m not sure what I should do if it does:
- Should I try cleaning the sensors again?
- Should I spend the $200 to replace both O2 sensors?
- Should I try cleaning the catalytic converters with “Cataclean”?
- Should I do a combination of those options?
- Is there anything else I should do?
I’m not sure if the O2 sensor(s) are dirty or if they are breaking. I’m unsure if the first catalytic converter is dirty and needs to be cleaned or replaced. I’m worried that the excessive oil consumption with the original engine had fouled and possibly ruined the catalytic converters. The old engine burned a ton of oil, so I guess it would be likely. It burned 1qt every 250 miles at its worst.
What should I do? Any advice? Please and thank you!
TLDR: 2014 Santa Fe Sport, 2.4L, 80k miles. P0420 code came up. Code came up last spring too, stayed away after cleaning O2 sensors. What should I do this time? What are any possible causes and solutions?
P0420 troubleshooting is in our FAQ. See if that helps.
Turf the "cold air intake". You drive a kid-hauler.
Cleaning is simple and doesn't cost anything. the next thing is the cat cleaner which cost a little money. Before I would buy replacements you might get a more comprehensive scan tool that tells you the real time readings. Sound like your injectors are running the car to rich. That would also explain the gas mileage issue.
The code hasn't come back yet, but if there's really a big issue, I'm sure it will soon. There's only one recent change to the vehicle that I would think may have had an effect. I was running a tank of 89-octane, ethanol-free fuel because that's all that a gas station had near me at the time. I then switched back to 87-octane, 10% ethanol fuel, which is what I typically run. Other than the decreased mpg and the prior code, my vehicle seems to be running fine. No lack of power or anything like that