Troubleshooting: Fuel, Air, Spark
Basic tune ups are good to do. You can easily clean the throttle body and intake components with carb cleaner and a rag. As far as the fuel system, Honda fuel systems are pretty good. (says Eric, a few others, and my car) I will occasionally put seafoam in the system but its not often necessary unless you drive your car less than a 1/4 tank often as sediment from the bottom of the tank can get sucked into the lines. If you really wanna you can do a fuel pressure test to see if its up to par. If not then it may be a clogged fuel filter.
You can tell if the fuel pump is bad by listening to it. It will make a loud whining noise that you can hear by the tank filler if its bad. But I doubt thats it.
The simplest thing is to check your air filter if you haven’t already.
Whats coming to mind is a clogged exhaust. If your cat converter is damaged and clogged that will choke your engine. It will take a moment to adjust when starting up if it needs to work harder to exhaust.
As far as the 0420, its not always the cat converter. Since it’s a pilot I’m assuming a V6 with two banks. So the code should specify which cat, unless there is only one. But it can be the downstream o2 sensor or and exhaust leak too. You can verify this by a few tests:
- Knock on the cat converter with a tool. If you hear rattling then the honeycomb inside is broken and you need a new one.
- Use an IR Thermometer if you have one and measure the temp before and after the cat converter with the engine warmed up and at 2500RPM
- Have autozone scan the car but take a look at the upstream and downstream voltages. At 2500rpm you should see the two voltages changing but not consistently the same as each other. If the two are the same voltages then you have a poisoned cat converter that is not working.
I only suggest these things because I find that many dealers just change parts on older cars rather than repair. Plus they can make a lot of money off a new one. Edit: EPA Law states that cat converters are under warranty for 8 years or 80,000 miles
If you do need a new cat converter and there is no warranty then look on eBay. A quick search tells me that you do not have to pay more than $230 for a new one. They are also bolt on’s so you could do it yourself if you’re good with bolts. Or you can pay a trusted mechanic. It shouldn’t be more than an hour or so. Also, often times the downstream and/or upstream o2 sensors should be replaced with the cat converter. If you need to also search on eBay. First go to Denso’s site to find the correct part for your car. I paid $40 for an upstream Denso sensor. Thats basically OEM Honda. Anywhere else would be $80-300. And always ask for the old part. You can sell your old cat converter and get around $100 back for it.
And the last thing is that if you have an 0420 and your cat converter has gone bad then that usually means there’s an underlying issue. Coolant or excess oil can get into the exhaust and poison the cat converter. Or your car can run extremely hot and destroy it. These are problems that are often missed or unknown and the converter is just replaced.
Basically a bad cat converter itself won’t cause any damage but it may mean there’s another problem. Then again a pretty hard smack by an object on the road can break it apart too.
So verify the issue soon and don’t pay anymore for the repairs than you have to.
Thats my speech.