I'm getting a p0420 and a p0457 on my 2005 2500 hemi ram... I only get them together never separate .. I know what both mean just wondering if there related... I've put all 4 new o2 sensors and and checked my gas cap and its good.. Has anyone done a PCM re flash for this issue... Any advice will help

 

What 02 sensors did you put in? Some guys have had issues with Bosch. Is it time for a tune up? Throttle body cleaning?

 

Sorry I made a mistake the code was p0457 NOT p0357... And yes just did a tune up plugs PVC air filter

 

You didnt answer the question about the o2 sensors. Did you use bosch?

P0420 indicates a faulty CAT I believe, but can sometimes just be a faulty downstream sensor. So swapping the sensors is not always the fix but is usually the best and cheapest first step.

 

P0420 could mean lots of things. Bad cat, lazy o2 sensor, cracked exhaust manifold or other exhaust leak. 457 is an evap leak. Best thing to do would be check all your evap lines and connections for cracks. I've heard there are problems with the lines at the tank.

As for the 420, since there are so many variables the best thing to do would be take it to a shop for a diagnostic. Yes it costs money but it's better than just throwing parts at it and hoping it goes away.

 

Used ngk sensors