My '05 Ram 5.7L is pulling O2 sensor codes. Autozone told me there were 2 sensors before the cat and 2 after the cat. The parts were priced at $29.99 each (before cat) and $34.99 each (after cat). Does that sound decently priced and is it true that there are really 4 sensors on these 5.7L engines? Also, is there a way to find out which one(s) really need replacing or do I just have to go through and replace all of them?

 

Oh forgot to mention, when Autozone checked the code for me it said there was a problem in bank 1. Does that mean its after the cat?

 

Is that the oe part or the universal? Those are good prices. for my 02 with the 5.9 they are $75 a piece.

 

they are about $65 each from the dealer. I wouldnt buy universal ones

 

You have two cats....one for each bank/side of the engine. Each cat has a 02 sensor before and after it...the pre-cat o2's help adjust the a/f ratio and the post-cat o2's monitor the cat efficency. That;s a good price for o2's but they're geniric universal ones...probably made by bosch.


Each o2 has several dtc codes that can be thrown...and they vary slighty to show you which o2 is throwing a code. Bank 1 is the driver side and bank 2 is the passenger side...sensors 1 are the pre-cat o2's and sensors 2 are the post cat o2's. Post the codes you have and we can help you...or you can search google for obd-II dtc codes.

 

I agree, don't buy universal sensors for the Dodge.

 

Thanks for the info guys. i found the receipt they printed for me at autozone and i'm not sure if this is a code but it says : Troubleshooting P0420 and it is an OEM brand OBDII. It describes the code saying "The PCM has determined that the catalyst system efficiency for bank 1 is below threshold for the current engine operating conditions "

 

Theory of Operation The State of Change (SOC) catalyst monitor uses the signals from both the upstream and downstream O2 sensors to detect aging of the catalyst. Based on the fact that when a catalyst ages, it loses some of its Oxygen Storage Capacity (OSC). As a result, part of the untreated exhaust gases can breakthrough the catalyst and causes the downstream O2 sensor to deviate from its neutral (Stoichiometric) position. By observing the activities in the downstream O2 signal, the degradation level of catalyst can be detected. In general, the higher the downstream O2 sensor SOC value, the more exhaust gas breakthrough and the lower the OSC of the catalytic converter

 

It could be either or both O2 sensors...
Factory upstream left or right. Part # 56028994AB and retail for $47.20
Factory downstream left or right. Part # 56029049AA and retail for $44.10

 

p0420 is the rear o2 on the driver side....do you happen to have headers on your truck? That is the code most people get when long tube headers are installed.