Drive Accord Honda Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter · #1 ·
Hey Guys,

I have an issue witha 2003 Honda Accord 2.4, with 285,000 kms on it

I had the CEL light come on as well as some type of fumes coming into the car when the heater blower was turned on. As i was constantly getting a headache and watery eyes when driving it, it does burn oil but generally the car runs great.

I had it scanned and the code was p0420, i took it to three shops and they said it ws the Cat, and the O2 Sensor (Upstream), also none of the shops said there was an exhaust leak, and they could not see where the fumes was entering the car.

$600 bucks later i replaced the CAT, and the O2 sensor, after 75 clicks the CEL light came back and the fumes/smell are still entering the car when the heater blower is on. The shop said they did a heat test on the CAT and it was failing and the upstream O2 sensor was not working properly (had it on a graph machine).

I took it back to the shop and now they are saying to replace the Downstream sensor, so just wanted to ask if i should do this or is there another issue i should be telling them to look for. Also anyone have an idea about the fumes coming into the car if there is no leak on the exhaust or oil leaks on the car, i did change the PCV valve.

Thanks
 

·
Registered
Joined
·
1,279 Posts
The P0420 code is for the converter efficiency which is measured by the downstream O2 sensor. If the upstream sensor is not working properly is should set other codes. What brand of upstream sensor was used when it was replaced? NGK or Denso usually work best on these cars. Vacuum leaks and other engine problems can cause the upstream sensor to work improperly.

Is the new code still P0420 or something else? Replacing the downstream O2 sensor may or may not fix it. If you search P0420 you will find other solutions for getting rid of the code. The oil burning will shorten the life of your new converter, but it should last more than 75 clicks.

The exhaust fumes getting into the car might be coming from the trunk seals leaking. Are they in good condition?
 

·
No Gears, Got CVT :)
Joined
·
550 Posts
I'll tell you my story with my 2003 Accord I4. This may not be the same problem as yours but maybe it is.

I got the car new in Feb 2003. Less then a year later I got the P0420 code. Sometimes it went away, then came back. The dealer said it was the CAT and replaced it. I told him something else must be wrong because it is too soon for a bad CAT. He said sometimes it happens.

Same thing happen again less then a year later. This time he changed both the CAT and O2 senor.

The third time it happen he found a Technical Service Bulletin and said the computer needed a firmware update. He also had to change the computer because my Accord was build in Japan, not in Ohio. He did not change the CAT or O2 senor this time.

Never had the problem again after the firmware update. I sold the car in Oct 2012 with over 142k miles on it
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #4 ·
Ok so here's an update took the car back to the shop and they hooked it up to a scanner which had graphing capabilities , they told me the after cat sensor was faulty as it was giving a range of 0.9 to 2.5 and this was high they said it should be flat lined. Because of this the car was running rich hence the p0420 code


They said if I replace this sensor the car should be fine saying they were %85 certain this wAs the fix. Before I go do this wondering if anybody had any thoughts or suggestion. Already replaced the pre cat o2 sensor and the cat.
 

·
No Gears, Got CVT :)
Joined
·
550 Posts
How long have you owned this Accord?

If it not too long, I would ask a Honda dealer if there are any outstanding TSBs for the P0420 check engine code for your VIN, especially if it has to do with a firmware update like mind was. I would think checking for a TSB should be free. Your car is out of warranties. Most likely there will be a charge for installing the TSB.

If you had the car for years with no problems, then the sensor may be it.
 

·
Banned
Joined
·
13,101 Posts
As for fumes- I like the cheap and quick method.

Pour some Seafoam into the vacuum intake of a warm, running engine. Turn the car off and wait ten minutes. Start the car, then rev engine while you see where the white smoke is entering your car.

When Seafoam burns it produces white smoke. If there is a leak in a joint or any part of the exhaust- you will spot it. You on the inside, a friend on the outside.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #8 ·
Could anybody advise me on the following after changing the precat 02 sensor and the cat I can smell gas in the car as soon as I open the door prior to starting also the economy has worsened and still the CEL light

I am thinking that changing the pre cat O2 sensor the car is dumping gas into the cat and there is a lot of unburnt fuel, would changing the post cat sensor fix the engine from running too rich, or do I have other issues. Any information what the post cat o2 sensor does.

Any help would be greatly appreciated.
 

·
Banned
Joined
·
13,101 Posts
I can smell gas in the car as soon as I open the door prior to starting also the economy has worsened
Did/Do you overfill your gas tank? If you flood the evaporate fumes canister with liquid gasoline then you will always smell gas in your car thereafter.

Also, the economy has improved somewhat....:) Not sure what that has to do with your car.
 

·
Registered
Joined
·
1,310 Posts
I had the code, found a low mileage used cat on eBay with upstream pipe and both sensors attached for $200. So far no more code.
 

·
Registered
Joined
·
305 Posts
Emissions are not required in my county so I just got the spark plug defouler rigged to get rid of the pesky cel and retain my gas mileage
 

·
I <3 My Honda
Joined
·
3,245 Posts
As for fumes- I like the cheap and quick method.

Pour some Seafoam into the vacuum intake of a warm, running engine. Turn the car off and wait ten minutes. Start the car, then rev engine while you see where the white smoke is entering your car.

When Seafoam burns it produces white smoke. If there is a leak in a joint or any part of the exhaust- you will spot it. You on the inside, a friend on the outside.
this.Advice = great.Advice; :yes:

I love Seafoam!
 
1 - 12 of 12 Posts
Top