Hey Guys, I have been a reader on the site since I purchased my 2003 Discovery SE a few weeks ago, but this will be my first time posting. I did some reading on all of the previous posts regarding these codes that I could find, but I'm hoping some of you guys may be able to help me out. As mentioned in the title, I am having some issues involving the codes P0130 (bank 1 sensor 2) and P0171 (bank 1 system too lean). My Service Engine Soon light came on about two weeks ago and the truck was idling very rough while in drive. I took it to a local shop and they suggested replacing the 02 sensors. Well, I bit the bullet and had this done on Thursday and lo and behold on Saturday it started running rough once again, and has the same two codes once again. When I picked the truck up they mentioned that I have a very small coolant leak and I should get it taken care of soon. It appears that the coolant could be leaking onto the 02 sensor, but could it have caused an issue again that quickly, between Thursday and Saturday? I have been able to do some minor things here and there since I purchased the truck, but this is outside the realm of my current capabilities and taking it to the shop is quickly breaking the bank...I would greatly appreciate any input!

 

A sensor's electrical connector can become worn, corroded or leak causing a system to malfunction. Shops typically troubleshoot/change parts after doing a code scan and don't get into electrical issues unless the problem/customer comes back. Does it appear that your O2 sensor plugs are being dripped on by the small coolant leak you mentioned?

 

You, being the owner of a 2003, should be aware that your temperature gauge on the dash cluster doesn't begin moving towards the upper/ red until the coolant gets quite hot. If you haven't read in the threads already, you should be monitoring your coolant temps with some form of aftermarket gadget. These trucks tend to run hotter as they get older so the first thing that you should do is make sure that truck is running around 200 degrees at operating temperature. Also, if you cannot borrow a pressure tester then you can rent one from advance auto or some other big box retail parts store but be aware that you will have to find an adapter to connect the pressure tester to the overflow tank if you cannot get the Advance Auto version, or so I have read. You can also crawl underneath the vehicle while the engine is running at operating temperature to search for the source of the leak. It can be anywhere on the passenger side of the engine or under the throttle assembly on the driver side. This model of trucks have a hard time maintaining any kind of consistent operating temperature, much, much less with a leak. You are probably having major temp swings which will lead to head-gasket failure, cracked block, slipped cylinder sleeve---just to name a few. A 2003 Discovery is nothing to play around with. Doesn't take much for a catastrophic failure so I suggest you stay on top of that. I wish I had advice on your codes and rough idle but I have not encountered that. Plenty of coolant system - related issues though! Like I said, take it seriously and get under there and look around and figure out what kind of engine temps that you have going on