Hello all,

BLUF: Honda Accord 2.4L bogs down while driving and losses power until it shuts off, even while driving. Will not rev above 3000 RPM.

This car has 225K miles and it's been intermittently throwing a P0420 for a while now, but no significant issues in gas mileage or oil consumption. It's suddenly been bogging down while driving and shutting off when I pull over. I'll restart it 7-10 times and it will vibrate and shut off in a few seconds. When giving gas, it'll shutter and die more quickly. Eventually, it'll stay on and I can drive until it repeats a few miles down the road.

There are now several codes and they are:

P0420 - Catalytic System Efficiency Below Threshold Bank 1
P2195 - O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1
P0139 - O2 Sensor Circuit Slow Response Bank 1 Sensor 2
P0171 - System Too Lean Bank 1
P0116 - Engine Coolant Temperature Sensor 1 Circuit Range/Performance

I am going to start looking into the codes separately, but I have a feeling there's one issue that's causing the codes all at once.

I've replaced the O2 sensors same times in the past, but I don't remember when. I've been doing research and there's a lot out there that's difficult to keep track of what could be viable causes. I'm going to look into the MAF sensor, ECT sensors, VTEC sensor, O2 sensors.

Please, share any info that could point me in the correct direction and if you've had a similar issue.

 

As an update, I removed the upstream O2 sensor and drove up and down my road. I think it's a clogged catalytic converter because the codes have gone away, and I am not losing power. It seems to be an intermittent issue as it hasn't happened again. Thank you for the reads.