2005 Ford 500 Tune-up & catalytic converter replacement

Tiny
JAMALB09
  • MEMBER
  • 2005 FORD 500
  • 102,000 MILES
I took my car to a mechanic because the check engine light was on. The codes he got when he did a reading were P0420, P0304, & P0300. He did an inspection and found that I need all catalytic converters replaced, oxygen sensors, spark plugs & ignition coil. I'm taking my car to be repaired and most likely will have to go to two different shops. Which repair should I get done first? The catalytic converters/oxygen sensors replaced OR the spark plugs/ignition coil?
Do you
have the same problem?
Yes
No
Friday, May 31st, 2013 AT 11:36 AM

2 Replies

Tiny
CARADIODOC
  • EXPERT
P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
P0300 - Random/Multiple Cylinder Misfire Detected
P0304 - Cylinder 4 Misfire Detected

Your first stop should be to a different shop for a second opinion. I don't know which engine you have so I don't know which type of ignition system you have but there are too many parts being replaced here. I could believe an ignition coil but the 420 code is detected by readings from the rear oxygen sensor(s). You don't replace the messenger because you don't like the message. If that code was detected the oxygen sensor has to be working. If it was not working a different code related to that would have been set.

The misfires could damage the catalytic converters if they were bad enough but there should have been some warning first. The Check Engine light will flash if too much raw fuel is going into the exhaust system and will overheat the catalytic converters. Random misfires will be detected but usually aren't bad enough to overheat the converters.

The exception is if the Check Engine light turned on and you ignored it for a long time. That will give other parts time to fail. All the parts you listed can set diagnostic fault codes. They didn't all fail at the same time. I would start by replacing the spark plugs, and replacing the spark plug wires if your engine uses them. Erase the fault codes, then drive it and see if any codes set again. If you get a code related to catalytic converter efficiency, you replace the one listed in the code, not any others.
Was this
answer
helpful?
Yes
No
Friday, May 31st, 2013 AT 11:51 AM
Tiny
JAMALB09
  • MEMBER
Well after I got the diagnostics done, I took my car to a muffler shop. They checked the whole exhaust system, and checked the "back pressure" on the converters. They also recommended that I replace the spark plugs, the four oxygen sensors on the front two catalytic converters, and ignition coil. I was shocked & confused when they said I needed to replace all three catalytic converters. Since the dealer said I only needed to replace one (Bank 1), like you said.

As for the check engine light. I took my car twice to get checked. Once in January, they told me it was ok there was nothing wrong with my car. Then again in April, they said it was an (Evap code)? Caused by running your car while pumping gas or not tightening the gas cap all the way. And that I needed to replace the gas cap. Confused again! So I continued driving my car, not knowing that there was something seriously wrong with it. And now I'm about to be out of a couple thousand dollars!

THANK YOU SO MUCH FOR RESPONDING, I REALLY APPRECIATE IT!
Was this
answer
helpful?
Yes
No
+1
Friday, May 31st, 2013 AT 12:25 PM

Please login or register to post a reply.

Recommended Guides