hey guys today i've been driving my 97 dodge ram 1500 auto 4x4 all day, got off work and took it to the store and my check engine light came on. checked the oil and it was low so i added some and its still on(didnt think that would work anyway) scanned it and it was po420 catalyst..threshold....Bank 1. did some research and found it was either catalytic converter or o2 sensors. called magnaflow to order a converter but he was saying if some thing caused the converter to stop working from the motor that it would happen again so to address what caused it also. so what should i do and what could cause it to stop "filtering properly" truck has 122,200 miles also if i do o2 sensor should i use bosch or ngk thanks for the help.

 

check your plenum, if its blown you are getting oil blowby into your exhaust, common problem is that it blocks up the converter. thats where i would start. its really easy to check take off you TB and look down into the manifold see if there is oil in there, grab a small mirror and look for pooling in the back.

do a search there is probably about 10000 or more threads on the plenum subject.

 

i know i have oil leaking from what looks like the valve covers, maybe the rear main seal but it might be the valve running down the bell housing, but ill check the plenum, ive read about it and assumed its leaking so i should check/replace the plenum, then get new cat and o2 sensors? anything else to check. thanks

 

p0420 is not a serious code. it means that the rear O2 sensor is reading emissions the same as the front O2 sensor, which implies the converter is no longer scrubbing the exhaust.

it is not necessarily a "stopped up" cat, although it could be a bad cat, or bad front o2 sensor, or bad rear o2 sensor.

unless your truck's plenum has been fixed, its likely leaking and might be burning a lot of oil, which does contaminate the cat, and cause you to be constantly low on oil. so - a lot of problems stack up on top of each other.

wow. your 97 has really low mileage at 122, but its also probably due for o2 sensors.

i'd internet shop for best price on ntk/ngk, but before you do, unplug yours and check the shape of the connector. round or square. all the application guides seem to be wrong, so it helps to know the shape. replace o2, see if it fixes your problem or not. then monitor/plan a plenum fix, also your due for a water pump - which leads to a whole top end strip down, tune up, etc.

http://www.p0420.com/

 

i'd start with the cheapest and easiest things first.... which is o2's.

 

i looked at kragen oreily and they have bosch and ngk o2 sensors, which is better for the dodge?

 

also i think i have four sensors so should i replace them all?

 

4 o2's will be expensive.

P0420 is bank 1, which is drivers side.
i'd probably start with just the drivers side, post-cat (rear). why waste money.

 

DO NOT GO WITH BOSCH!!! Go to summit racing or jegs and order the NTK o2 sensors. Thats what i think is wrong with my truck right now damn bosch o2sensors

 

which is which one? i think theres one on the driver header flange, passenger header flange, above the cat and below the cat, so is it the driver header flange? also ntk/ngk or bosch?