Hello all,

2013 Honda Fit base with 65k miles

My honda dealer replaced my Cat under warranty after it threw an error code P0420. The check engine light came back on a few days later. The light has turned off and on a couple times before the cat was replaced, and now it turns off and on after.

Now Honda tells me my valves are too tight. The diagnostic sheet reads that the "AF ST is at .94 and should be at 1" and the MAP is at .98v and should be at .8V

I understand the need for the valve adjustment. But they're also recommending that the Air Fuel sensor be replaced. Is this part necessary? They also suggest replacing the spark plugs while they're in there, which i'm also not opposed to.

Can someone explain this diagnostic to me a little further? just trying to understand what is going on. I plan to have the valves adjusted, but is it safe to drive in the meantime? Thankfully I work from home and don't drive much, but would like to have an idea.

Thank you everyone.

 

The "air fuel sensor" is the oxygen sensor. You have an upstream sensor and a downstream sensor.

If I had to guess, I'd say the catalytic converter wasn't bad to begin with and you really just needed a new O2 sensor.

Did you buy the vehicle used? Asking because I'm wondering about the possibility of more miles than it's showing or the possibility that it has had bad or poor fuel run through it.

Regardless, changing the plugs isn't a bad idea given that it has a reported A/F ratio issue. Plugs could be the culprit.

Valves should not need adjusting yet. 90k miles is the normal interval for the GE Fit. You're quite a bit short of that unless it has more miles than is showing.

 

Thank you for the response, the information is helpful. I didn't know the plugs could be the culprit or the typical valve adjustment range.

It was bought new. I can't say for certain the fuel that has gone in it has never been bad, but for what it's worth I always buy non-ethanol and in the last 5 years has always been from a newer gas station.

wondered that the cat wasn't bad to begin with as well. I explicitly asked the dealer if it could be anything else, and they were insistent it could only be the cat. Thank goodness it was warrantied and not something I had to pay out of pocket, I'd be mad! haha. I'm taking the car to a trusted local mechanic at their soonest appointment in a couple weeks to see what he says. I had taken it to the dealership for the cat since it was a Honda warranty thing, but I have more faith in the local mechanic.

Thanks again for taking the time to give me some useful information