My '05 RAM 1500 Crew Cab 4x4 has 128K miles.
Recently the truck started hesitating from a stop and would then surge, with the engine light flashing. I had the dealership look at it.
This is from their write up (minus the all caps):
"Owner states on take the engine/truck would shake...check engine light is on. Has acted up on hard acceleration. * Tested and verified the following codes P0157-oxygen sensor 2/2 voltage low, P0300-multiple cylinder misfire, P0132-oxygen sensor 1/1 voltage low. Tested all 3 sensor circuits and all the circuits test good. Replaced the 3 failed sensors and the owner requested to replace the 4th one as well. Cleared codes."
They installed 2 each 56028994AB and 56029049AA.
I also had them do a tune-up and cooling system flush at the time. Because the wife insists that the dealership maintains her car and the truck, especially as I am away on business quite a bit and she drives both vehicles (the truck during the winter).
The next day the check engine came on again, but it was not acting the same as it was previous. The thought was it might have thrown a code from the sensors previously having an issue. The code was cleared.
A few days later the truck started acting the same as before, this is their write-up:
"Check engine lamp comes on again. see history ** code P0402 for catalytic convertor efficiency. **Need to replace the catalytic convertor est of $1635.00 to replace catalytic convertor."
They charged me $80.62 to tell me the cat(s) needed to be replaced...
So, my questions are:
Was the issue with the cat or cats the issue from the start?
Should they have recommend the cats be replaced when they did the original work on the O2 sensors?
Should I decline to pay for the "inspection" or could legitimately trained technicians really not have identified the cats were the issue during the original work?
On a separate not, I have no plans to have them replace the cat(s). I am thinking that this is an opportunity to replace the entire system with something that is an improvement over stock.
I live in the country, do not have an emissions test, I occasionally tow with a trailer/tow dolly, the truck has enough power for our needs, and an increase in noise is not an issue.
What is a recommendation for an exhaust system that improves fuel economy?
If I decide to replace just the cats, are there inexpensive cats that will not cause the engine to throw codes? All of my older vehicles with O2 sensors are just a single pre-cat sensor near the manifold, so I have no experience with a system that needs post-cat sensors.