Hi everyone, I have had my Disco since May, and through that time my check engine light has been on, and i've slowly been correcting all of the problems, and now i'm down to the last code. It tells me that my "LH Catalyst Efficiency is below Threshold", which means that my cat is no good right?

Anyways, my vehicle does have a newer engine in it, because the previous owner drove it without antifreeze until the engine seized up. Could that have caused the cat to burn up? One thing that is very strange is that the light will turn on for maybe a day or so, and then turn off after a couple days. Is that normal? I have noticed that the shop that installed my engine was not careful with the wires as i have had to replace quite a few of them. Would a bad wire on my o2 sensor cause this code to come up? Usually when the 'check engine' light comes on, i'm at a stop light and the engine will miss a couple times (you can feel the vehicle shake).

My dealership told me that a bad cat would "affect my mileage greatly" as he put it, but i seem to get pretty decent. Is having a bad cat not good for a vehicle? I have noticed soot on the exhaust tip, but besides getting a little soot on the exhaust, should i be worried? Thanks in advance everyone!

 

its possible it could be causing an issue. but 0420 or 0430 mainly means a bad cat. very rare, you might be able to get it replaced if it is within 8 years 80k due to federal emmissions.

 

Who told you it was OK to drive with your check engine light on?????????????????
Because of that, and depending on what the other fault codes were, you probably burned out the cat, not a wise move.
Go find a muffler shop that can cut that one out and install a new after market cat, then pay attention to the check engine light in the future.

 

You are out of the warranty period with 95K, but you are nearing the threshold for replacing O2 sensors. Tke a rubber mallet and bang the cat you think is bad. If you hear stuff rattling around, it is bad. Replace it. Magnaflow makes high flow replacements that some have gone to on here. Cost me $250 installed vs $500 for the downpipe alone, not installed.

 

My LH cat has been showing bad since i bought the vehicle. The other fault codes were the MAF, a knock sensor (which after replacing it, i found out that it was just faulty wiring) as well as an o2 sensor, which also showed to be faulty wiring lol. The light has been off for about 4 days now, but i'm sure it will come back within a week or so.
okdiscoguy: where did you get your cats from? And who did you have install them?

 

ordered from Magnaflow and installed at a shop around the corner. If you go to their website, they have a dealer search to find a close one.

a stuck injector and a leaking head gasket can melt your cat. Bad news is your truck is running rich and you are carboning up your heads. Need to get it fixed soon.

 

How would i know if one of my injectors are stuck and/or if my head-gasket is leaking? Thanks in advance! :-)

 

inspect the spark plugs any that look very clean or have a rusty tip have coolant being ingested .
Get a block tester at NAPA 50.00 this tests the coolant system for hydrocarbons in the coolant

 

If you have a leaky injector, you will have a 200 type fault code, like a 201 for a bad injector in # 1.
As for head gaskets, you'll be loosing coolant either internally or on externally as well as oil externally.

 

hmmm.... I get 0430 code and Mike you told me it was probably failing... then I found my Y pipe manifold gasket was loose so tightened and 0430 stayed off for awhile but now occasionally back on... I was thinking... is it possible to get a 0430 from a failing downstream O2? or would I get that code also? I only get the code occasionally .... I replaced my upstream O2s and tightening the manifold gaskets ( y pipe ) made world of difference