I have an '04 V6 Accord EX and it's currently (and has been for the last few days) throwing codes:

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

So I'm trying to figure out what is causing this without changing a bunch of stuff... I know it could be the MAP, MAF, O2 sensors... air filter... or something else....

Also last winter I did get a P2195 O2 Sensor Signal Stuck Lean Bank 1 Sensor 1 code, but the check engine light went away and code cleared before I could change the sensor so I figured maybe it was just a loose connection or transient... and it's not throwing that code now.

So suggestions where to start troubleshooting first? I figured I'd replace the air filter and MAF sensor to start, but would you recommend starting elsewhere? Thanks.

 

Don't throw any parts at it until you do some diagnostics. I've seen new parts fail out of the box and further complicate solving the original problem.

Do you have a scanner and can you read some live data?

 

So I got a scanner, when you say read live data what exactly do you mean? The scanner is still showing the the same P0172 and P0175 codes. There is also an option that says “view freeze frame” which seems like a freeze frame of live data, but what am I looking for in there?

Thank you again.

 

*bump*

Anyone have any advice here? I need to get this fixed because I have emissions due next month… I really don’t know what to do other than getting parts and starting to change them… if anyone has a suggestion I’d appreciate it thanks.

 

To start you need to verify if your Accord is running Rich or that the computer is deciding this as you need a software up. If it is running Rich is it because of an engine miss. Your mention of an O2 sensor is something that could give you a Rich condition.

 

Just post the freeze frame data on here. A screenshot would work. That is the live data stored when the error code was set. That may give you a clue of what is going on.

Some scanners can read live data when the engine is running. What kind of scanner do you have?

 

My scanner does a freeze frame

 

A sudden check engine light for both banks running rich, means the engine computer is removing fuel on the front and back 3 cylinders to get the O2 sensors to monitor normal exhaust.

Your scanner looks to only read codes and can't read live data, so your testing will be limited with your current scanner.

A rich condition can be caused by restricted air flow, too much fuel added by the injectors, O2 sensors not reading the exhaust properly, bad fuel, or possibly an exaust leak.

Check that the air filter isn't completely clogged. It won't hurt to replace as it is a maintenance item.

Any chance you filled up your gas tank just before you got these codes?

Was any work done on the car just before you had the codes?

Your accord doesn't have a MAF sensor, so it runs off a MAP sensor. Since you aren't getting MAP codes, I'd hold off replacing the map sensor. I've rarely seen them fail and they should cause their own code.