Hi y’all! I have a 2009 Fit with 166,000 miles. I’ve recently replaced the catalytic converter (front only) and have been getting the P2101 code in addition to P0420 for the cat. When idling in Drive, it would have a rougher idle, the engine would make jerking motions, and it seems as if it would stall. This is intermittent, worse when the weather is cold. This issue does not happen when idling in Park. I had a mechanic friend clean out the throttle body which definitely helped with the choking issue for about a week. Then, when idling at a stoplight, the engine shuddered, revved up to about 2000-2500 rpm, and then I lost the use of the gas pedal. The car was still running, and would move forward without acceleration, but very slowly. Turning the enging off and then back on resolves the no acceleration issue, but the light is still on. So far, the loss of my gas pedal has happened 4 times, 3 before cat replacement, and once after, and only when idling, not when the car is driving/in motion.

I had hoped that replacing the cat would improve things after having the throttle body cleaned, but it’s looking like I need a new throtle body. I would like to know if anybody else has experienced this issue, specifically the two issues together and whether they are related or not. My cat went bad at around 130,000 miles but it took me about a year to get around to servicing it. The throttle body issue has only been recent, as of maybe two months. The cold weather seemed to make it much worse.

Any advice is appreciated. Thank you!

 

Why did you changed the catalytic converter in the first place?

P0420: "Possible causes: Three way catalyst converter Bank 1 Exhaust tube Intake air leaks / Fuel injectors may be faulty / Fuel injector leaks Spark plugs may be faulty / Improper ignition timing Engine Control Module (ECM)" Read more: https://www.autocodes.com/p0420_honda.html

P2101: "Possible causes: Faulty Throttle Actuator Control Actuator / Throttle Actuator Control Actuator harness is open or shorted / Throttle Actuator Control Actuator circuit poor electrical connection" Read more: https://www.engine-codes.com/p2101_honda.html

 

 

Sounds like there are a couple of issues, I can tell you that after cleaning/removing the throttle body, you have to reset the throttle position sensor. If you don't it will cause the idle to be rough and to surge. You probably do not need a new one (I thought the same thing and many sources on the internet will tell you that you need a new one as well) You may also want to check your accessory drive belt to make sure its in good shape and not slipping.

Here is a link to a video on the throttle position sensor. (it's for a civic, but this solved my issues)

 

OBD II error codes are clues to diagnose the problem, not an absolute pointer to whats wrong, nearly any malfunction in the fuel ignition system will throw the bad cat code..
Or bad O2 sensor codes, soon as you fix the main issue the cat and o2 sensor codes typically go away.. Unless you drove it running bad too long then the cat may be too fouled to burn itself clean..