Sorry about the double post. I messed up the title and it was not going to get any reviews or comments.

Good Morning, my sister bought a 2009 Range Rover Sport 4.4 HSE. She bought it about a year ago from the Land Rover Dealer in Newport Beach, Calif. Nice clean truck, soccer mom vehicle most likely. 114k miles. She just had the check engine light come on.
Codes:
U0155 - Instrument Cluster Control Module
U0073 - Control Module Communications Bus Off
P0420 - Catalyst System Efficiency below threshold Bank 1
P0430 - Catalyst System Efficiency below threshold Bank 2

I suspect that U0155 and U0073 are random codes due to a new battery or something along those lines. The P0420 and P0430 are a concern. It is odd that they both came on at the same time. Unfortunately she is in Salt Lake so I can't check it myself.
Recommending that she have the throttle body cleaned, MAF cleaned and run a tank of gas with a bottle of Techron. She is in Utah, so if it is the cats, she can get aftermarket options. No such luck here in California.

I have seen reports of people using spark plug defoulers on the O2 sensors on some vehicles to stop the CEL from coming on due to cat issues. Has anyone seen that on a LR3/RRS 4.4 ltr application? No need for a show of hands, I don't want anyone to get in trouble with the EPA, just wondering if anyone has seen that work. I know that it works on Toyota 4Runners both V6 and V8 4th Generation models.

Any other suggestions? thanks for the input.

Phil

 

The first 2 are likely phantom codes and I wouldn't be to worried about them. Any given time I can't tell you how many weird codes I have floating around.

Is she having any drive-ability issues? Cleaning the throttle body is never a bad idea. I would also check to make sure there is not air leaks on the intake

 

When I got these in my 2007 HSE, I usually dumped a bottle of Mr. Gasket Cat Cleaner in the tank, reset the code and waited the 6-9 months for it to show up again. After two years, I finally solved it by putting a spacer in the down stream O2 sensor. We have a lot of alcohol in our gas here in TX and it seems to throw the code more often with premium that with regular., and more so in the winter.

The wisdom of the internet says the O2 sensors are good for 80K-120K miles, but the cats should last twice that if the engine is operating properly.
With the P0420 and the P2096 codes it seems a good idea to work this cat cleaner and BG fuel system cleaner into your normal service schedules.

Anyway, that's how I fixed mine

Jeff

 

Rufflyer, can I ask what spacing the O2 sensor would accomplish in regards to it sending error codes?

 

 

First off, like Abran said, change the sensor. That is the best way to fix it.
Second clean the cat with a good cleaner like Mr. Gasket Cat cleaner. Reset the MIL.
Third, try buying gas at a different station (maybe one with cleaning additives) try only using regular and no premium. (many premiums gasses have a lot of ethanol which burns cleaner that gas and the cat does not do much work and so the downstream O2 sensor is not happy when the O2 levels from upstream and downstream are similar.

If all these trick fail to keep the code away for a few months at a time, an O2 spacer in the down stream O2 sensor will move it out of the exhaust stream just enough to reduce the amount of O2 it picks up and then it thinks the cat is working above the lower threshold limit.
At least this is what finally worked for me. I fought this code coming one every few days, then every few weeks then once a month, then it stayed off for 4 months before the car was flooded in Hurricane Harvey in 2017

General Disclaimer applies: I may be WRONG!

Let us know how it turns out.

Jeff

 

 

6 for 8! That would keep you in the majors with .750 batting average. maybe even in the hall of fame. (well, if not baseball hall of fame, at least here on the forum!)
I am 1 for 2 or .500 for this code being fixed with new sensors, so since you have more times at bat and a better batting average, I will agree that the sensor is the right way to fix it. But sometimes a spacer is the one that works, even if it is wrong.

Jeff