My "check engine" light came on this morning. My code reader read the following errors:

P0705 (http://www.obd-codes.com/p0705)

P0706 (http://www.obd-codes.com/p0706)

P0430 (http://www.obd-codes.com/p0430)

P0420 (http://www.obd-codes.com/p0420)

I have experienced no difference in performance, but it seems like I may need to replace my external transmission range sensor and my catalytic converter. Is there a way that I can more accurately diagnose the problem on my own, or does this require the expertise and expense of a mechanic?

Any input would be greatly appreciated.

 

Any recent work or damage done to the car?
That range switch(if both codes popped up at the same time) may have been damaged from an impact or flooding(big puddle). It's mounted to the exterior of the transmission so it can be damaged by road debris, especially if its protective metal cover is missing. Check it for continuity through the switch, if it checks out fine, check the wire harness to/fro the switch for damage as well.

P0430? Pretty sure even the V6s only had one catalyst so that's bull. Not to mention your codes should read P1705/P1706, not P0705/P0706.
I would try a different code reader/scanner and verify the codes you have.

As for the P0420 code, if accurate, that means the catalyst is performing below threshold efficiency. The engine is most likely out of tune, or has a random misfire but the PCM has not diagnosed or recognized it and simply has thrown out the P0420 code first. Our cars are Speed Density systems, they are not the best at accurate diagnostics.

When was the last time the car had a full tuneup? Plugs/wires/cap/rotor/O2S?
If the plugs are old they may have loosened/backed out of the head and are causing a leak, or if they are worn(too big of a gap) they may be not be fully igniting the air/fuel mix, which would lead to a partial misfire.

When was the last time the valves were checked/adjusted? If they have not been checked/adjusted in the past 30Kmiles the exhaust valves may be too tight and not properly sealing the cylinder, this would lead to a P0420 code.

A catalyst can clean up a lot of crappy emissions, but if the engine is dumping raw fuel or air, it will not not be able to function properly if the engine is out of tune.

 

Thanks for your input.

I tried a different code scanner, and P0420 was the only code that came up.

Any recent work or damage done to the car?
No damage. No recent work other than oil change. Axles and axle seals were replaced about 6 months ago.

When was the last time the car had a full tuneup?
Last tuneup was about 3 years ago.

When was the last time the valves were checked/adjusted?
I don't know the answer to this question.

 

Examine switch and wire harness for damage.
Check valve clearance and adjust as need be.
A tuneup with new plugs/wires/cap/rotor/O2 sensor/oil/oilfitler/air filter/PCV system check and if need be replacement of the valve or grommets.
Do not even think about replacing the catalyst until you have the engine tuned up and verified it is in good mechanical working order.

 

Hi I am new here and maybe somebody can give me some advice. My girlfriend has a 2007 Honda accord and her check engine light came on while ago I told her to go get it checked out and she told me that they totaled the car was fine but it was just a sensor. Later she mentioned that it was the Catalytic converter I told her to really get it physically looked at by a mechanic, but it never happened. Now the car just stops running while its in drive...and I mean in the middle of the highway. So I guess it's time to replace it.
I used to have 95 accord myself and the same problem happened it would just stop running out of nowhere. but back then nobody can figure out what was wrong with the car it was even at the dealership for a week and they couldn't figure it out I sold the car and the guy went to a scrap yard and replace it himself. But that's likely not going to happen with this car.
I was told that the car stops running because the fuel system is not working and because it's either clogged up or something is wrong it's not allowing the fuel to get to where needs to go.
so I guess my question is...
is there a place where I can buy the part online or maybe even a store so that I'm not charged an arm and a leg for it at a shop. We're both females so I know that if either one of us goes into a muffler shop or any other mechanic they may try to pull one over on us.
What is the estimated cost of this part or would it be better for me just to take it somewhere and have them provide the part and do the repair. Is it customary for shops to allow you to provide your own parts. My old mechanic would always let me do it that way because it was cheaper for me but I'm in a new city now and don't know if he was just doing that to be nice because we knew him for so long or if it's ok to do.
any advise or suggestions would be appreciated, thanks.