P0420 Trouble Code

[dflondro]

I have a 2006 4.6L Explorer. My check engine light came on. I purchased a OBD reader and found that the code was a P0420. I reset the code. I read in the owners manual to see how to get the vehicle emissions ready for emissions testing. I ran the engine through the profile but the OBD still says the vehicle is not ready for emissions test. I ran the vehicle for 3 more weeks and the check engine light came on again with the same trouble code. Has anyone had this issue? I am hoping to avoid having to buy a new catalytic converter unless it is really needed.

 

[swshawaii]

Hope you understand that clearing the p0420 code, or any DTC for that matter, does NOT fix the issue. Even if it's erased with your new "reader", trouble codes will remain stored in memory until corrected. The "Readiness For Inspection" process applies to vehicles after they have been repaired. Call around and find an independent exhaust/emissions specialist. GL

P0420 Catalyst System Efficiency Below Threshold (Bank 1)

Readiness for Inspection/Maintenance Testing

In some localities, it may be a legal requirement to pass an I/M test of the on-board diagnostics system. If the indicator is on, refer to thedescription in the Warning lights and chimes section of the Instrument Cluster chapter. Your vehicle may not pass the I/M test with the indicator on. If the vehicle’s powertrain system or its battery has just been serviced, the on-board diagnostics system is reset to a “not ready for I/M test” condition. To ready the on-board diagnostics system for I/M testing, a minimum of 30 minutes of city and highway driving is necessary as described below:

• First, at least 10 minutes of driving on an expressway or highway.
• Next, at least 20 minutes driving in stop-and-go, city-type traffic with
at least four idle periods.
Allow the vehicle to sit for at least eight hours without starting the engine. Then, start the engine and complete the above driving cycle. The engine must warm up to its normal operating temperature. Once started, do not turn off the engine until the above driving cycle is complete.

(Owners Manual Pages 310-311)
http://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/06expog2e.pdf

 

[dflondro]

Thanks!! I understand clearing the code will not resolve the issue. I would think that after running the vehicle through the readiness profile, either the check engine light would come back on for the same error code. I will have to take it in to have the sensors and catalytic checked.

Thanks!

 

[Flag Gibby]

In the back of my brain, I seem to recall that running E85 all the time can do funky things to the emissions system. Don't know if your vehicle is E85 capable or if you have been running E85, but just wanted to put that out there.

 

[makuloco2000]

Your cats are done for, replacement is the only repair, see it all the time on the 4.6l. You under 80k miles?

 

[gbasplen]

Reprogramming the PCM worked for me. A $89 fix by the dealer has kept the Check Engine light off for about 1 week and ~700 miles. Every test I did pointed to the Cat Converter. So far reprogramming the PCM fixed my problem for long enough for me to get through the state emissions check.

 

[Boomyal]

Reprogramming the PCM worked for me. A $89 fix by the dealer has kept the Check Engine light off for about 1 week and ~700 miles. Every test I did pointed to the Cat Converter. So far reprogramming the PCM fixed my problem for long enough for me to get through the state emissions check.

...for that matter, just use your tool to turn off the light before you take it in for the State inspection, then deal with the problem at your leisure.

 

[gbasplen]

I have tried that. The state of Maryland uses a tool that plugs into the OBD II port. The state's OBD II reader knows if the CEL has recently been reset. They asked me if I'd disconnected the battery recently. They wanted me to wait about 1 week and come back so the car had time to "re-diagnose" itself to see if the CEL would come back one.

 

[dflondro]

I had to replace the catalytic. The repair facility said it is a common problem. Thanks for the help!