Engine Light Code 0420
#1
04-01-2011, 06:33 PM
Engine Light Code 0420
This one could be complicated...
In my 99 Civic EX, which my wife primarily drives to work only 1 mile away, we had an engine light / code occur while my wife was driving the car 30 miles from home. The car ran poorly, almost killed on her several times, but she managed to get home. We left the next day for a 1 week vacation, and afterwards the light turned off for several days but then came back on and ran very poorly, so it was time to deal with it.
The initial code was 0301; a misfire in the #1 cylinder. The car has 115,000 miles on it, and had never had the plugs nor wires replaced, so I went to the local AutoZone and bought new Bosch plug wires & new double platinum plugs. Replaced both in less than 30 minutes, test drove the car, it ran great, and the light cleared itself. Problem solved!
Not so fast. Two days later my wife decides to take the car do "the big city" to get a muffler replaced (lifetime warranty). See, with her only driving 1 mile to work, the exhaust system never gets warm enough to evaporate the condensation in the system, and she's gone through about 5 mufflers & misc. exhaust system parts in the 12 years we've owned the car. Well, the engine light came on, was running hideously, and actually killed and stranded her on the road. Via phone, instructed her to check the plug wires, and #1 cylinder wire is off the plug and can't get it seated properly. She manages to limp the car back home the 15 miles. Take car to a mechanic, who finds that the new plug wire is faulty (clearly obvious once it's pointed out to me). Replace wires & rotor & distributor, car runs great, engine light goes off. Car fixed!
Not so fast. Less than 2 miles away from mechanic the engine light comes back on, but the car still runs great. My wife had errands to run and couldn't take the car back to the mechanic, so I dealt with it when I got home from work...after the mechanic is closed for the day. Take car back to AutoZone, this time it's code 0420...related to catalytic converter.
Remember that the muffler still needs replacing...it's now very loud and rusted badly inside.
The question is: Did running the car with such a poor misfire going on for that period of time (the attempt to "the big city") cause the catalytic converter to burn out?
The only other possibility that I can think of is that because the muffler is rusted out, would it potentially restrict the airflow to the point where it can't exhaust properly and cause the sensors to kick out the 0420 code? I'm not sure it can do that, but if a clogged catalytic converter potentially could cause it to have that code, perhaps the muffler being clogged could do it to?
Sorry for the length, but there's several factors that I felt may help to diagnose this and point me in the right direction. I just want to determine if I should only replace the muffler or consider the converter replacement too.
Thanks!
In my 99 Civic EX, which my wife primarily drives to work only 1 mile away, we had an engine light / code occur while my wife was driving the car 30 miles from home. The car ran poorly, almost killed on her several times, but she managed to get home. We left the next day for a 1 week vacation, and afterwards the light turned off for several days but then came back on and ran very poorly, so it was time to deal with it.
The initial code was 0301; a misfire in the #1 cylinder. The car has 115,000 miles on it, and had never had the plugs nor wires replaced, so I went to the local AutoZone and bought new Bosch plug wires & new double platinum plugs. Replaced both in less than 30 minutes, test drove the car, it ran great, and the light cleared itself. Problem solved!
Not so fast. Two days later my wife decides to take the car do "the big city" to get a muffler replaced (lifetime warranty). See, with her only driving 1 mile to work, the exhaust system never gets warm enough to evaporate the condensation in the system, and she's gone through about 5 mufflers & misc. exhaust system parts in the 12 years we've owned the car. Well, the engine light came on, was running hideously, and actually killed and stranded her on the road. Via phone, instructed her to check the plug wires, and #1 cylinder wire is off the plug and can't get it seated properly. She manages to limp the car back home the 15 miles. Take car to a mechanic, who finds that the new plug wire is faulty (clearly obvious once it's pointed out to me). Replace wires & rotor & distributor, car runs great, engine light goes off. Car fixed!
Not so fast. Less than 2 miles away from mechanic the engine light comes back on, but the car still runs great. My wife had errands to run and couldn't take the car back to the mechanic, so I dealt with it when I got home from work...after the mechanic is closed for the day. Take car back to AutoZone, this time it's code 0420...related to catalytic converter.
Remember that the muffler still needs replacing...it's now very loud and rusted badly inside.
The question is: Did running the car with such a poor misfire going on for that period of time (the attempt to "the big city") cause the catalytic converter to burn out?
The only other possibility that I can think of is that because the muffler is rusted out, would it potentially restrict the airflow to the point where it can't exhaust properly and cause the sensors to kick out the 0420 code? I'm not sure it can do that, but if a clogged catalytic converter potentially could cause it to have that code, perhaps the muffler being clogged could do it to?
Sorry for the length, but there's several factors that I felt may help to diagnose this and point me in the right direction. I just want to determine if I should only replace the muffler or consider the converter replacement too.
Thanks!
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