I have an '04 V6 Accord and emissions are coming up. So my car was throwing the following codes:

P0175 System Too Rich (Bank 2)
P0172 System Too Rich (Bank 1)

I know those are rather nebulous codes, and could be cause by a number of issues. It started sometime in May, then maybe like 2 weeks ago the check engine light went out for about a week, then came back on with the same codes.

So before I spending money changing out parts, I figured I'd check all of the connections in case it's a loose connection. I checked the MAP, MAF, oxy sensor connections, unplugged and replugged them, and also cleaned out my battery terminals as they were very corroded. That made the code disappear and I verified this with a code reader.

So I go for emissions later same day, and I get a REJECT (not failure) because the catalytic converter, evaporative system, and O2 sensor showed as "not ready" for emissions. So the emissions lady told me that if I've recently done work on the car it'll reset things and they can't do an emissions test. She told me to drive it for a week and come back after a week.

Thing is, this is my secondary beater car, and I maybe only drive it once a week... so what do I actually need to do to reset those systems to "ready" for emissions? Is it a time based reset (so it is only a week), or do I need to drive a certain number of miles, or go a certain speed, or what? According to chat GPT, I need to do the following, but how accurate is the below?For a 2004 V6 Honda Accord to pass emissions testing, the following criteria need to be met to get the catalytic converter, evaporative system, and oxygen sensor to show as "ready":

1. Catalytic Converter:
   
   • Ensure the engine is fully warmed up.
   • Drive the vehicle at a steady speed between 55-60 mph for at least 5 minutes.
   • Allow the vehicle to idle for about 5 minutes.
   • Accelerate to 45-50 mph for 2 minutes and then decelerate without braking to a stop.
2. Evaporative System (EVAP):
   
   • The fuel tank should be between 1/4 and 3/4 full.
   • Start the car and let it idle for a few minutes.
   • Drive the car at a variety of speeds, including highway speeds.
   • Let the car sit overnight and then repeat the process.
3. Oxygen Sensor:
   
   • Start the car and let it idle for a few minutes.
   • Drive the vehicle at a steady speed of 25-35 mph for at least 5 minutes.
   • Accelerate to 45-55 mph and maintain that speed for a few minutes.
   • Allow the vehicle to idle for a few minutes.

General Drive Cycle Procedure:

1. Cold Start:
   
   • Start the car after it has been off for at least 8 hours.
   • Let it idle for about 2.5 minutes with the AC and rear defroster on.
2. Accelerate:
   
   • Drive in a moderate fashion, accelerating to 55 mph at 3/4 throttle.
3. Steady Speed:
   
   • Maintain a steady speed of 55 mph for 5 minutes.
4. Decelerate:
   
   • Coast down to 20 mph without braking (deceleration phase).
5. Accelerate Again:
   
   • Accelerate again to 55-60 mph at 3/4 throttle.
6. Steady Speed Again:
   
   • Maintain a steady speed of 55-60 mph for another 5 minutes.
7. Decelerate Again:
   
   • Decelerate to a stop without braking.
8. Idle:
   
   • Let the car idle for 3 minutes.

Tips:

• Make sure there are no pending trouble codes.
• Ensure the fuel level is between 1/4 and 3/4 of the tank.
• Perform the drive cycle on a flat road if possible.
• Avoid excessive acceleration and deceleration.

If after performing the above drive cycle the monitors still do not show "ready," there may be underlying issues with the vehicle that need to be addressed.

 

The readiness monitors require drive cycles to set. This is to prevent people from cheating their codes and passing emissions testing.

If you have a code reader, you should be able to monitor the readiness codes. In Texas, I could have one not set and still pass, but it varies between states. You'll have to drive with mixed driving until the PCM gets the criteria needed to run the readiness monitors. I drive for about 30 minutes to get mine set. I think evap requires been 3/4 and 1/4 fuel level in the tank to run that check.

 

This is very different than the emission test I used to run in Michigan during the late eighties. Back then it was just testing tail pipe emissions at a certain RPM.
For what it is worth from reading web pages with rich mixture on a V6 Accord. I would check the O2 sensors.