99 Disco 2 Emission Failure Help! Cylinder 5 Misfire and O2 sensors
 

Ok so I have been reading these forums for a month or so getting all the routine maintanence up to my specs, and now it is time to join. Unfortunately because I am needing help I cannot find on what I am afraid may be an expensive venture on the discovery 2 I bought about a month ago.

It's a 1999 Land Rover Discovery 2 V8 with 91k miles. I took it for emissions today and it FAILED with the following 5 codes.

P0134 - O2 Sensor Circuit No Activity Detected (Bank 1 S
P0160 - O2 sensor circuit No Activity Detected (Bank 2 S
P0141 - 02 Sensor Heater Circuit Malf ( Bank 1 Sensor 2)
P0161 - 02 Sensor Heater Circuit Malf ( Bank 2 Sensor 2)
P0305 - Cylinder 5 Misfire Detected


The first two were cutoff the page but I assume they are same sensors

So far I've had to replace the water pump, and the throttle body coolant flange kit, to stop the coolant leak. I just changed the oil over to synthetic, and did a fluid and filter change for the transmission yesterday. I seriously doubt the previous owner has done any type of preventative maint. Or tune ups, so I'm sure the plugs and wires are stock.

It just recently started the skipping after its good and warm, and cruising around 40-50 mph. It does it just enough to be noticeable, and occasionally idles rough.

Any and all help will be appreciated!

I would replace all 4 O2 sensors.
Looks like 3 of them are bad for sure.

After you replace all the O2 sensors - you will be left with the cylinder #5 misfire.

If you can get to the plug - replace it with a new plug.

Reset all the codes

and see if any new codes arrive.

That brings me to another question, what code reader should I get? I've seen some for $70 up to $400 at a quick glance.

I will let others chime on the code reader.

I bought mine for $500 about 6 years ago.
It is heavy duty and expensive.
Reads generic OBDII. And has custom codes for VW, Toyota, Ford, GM and all that.


Any OBDII reader will probably work. But, you should get one which is the most Land Rover specific as possible.

Remember that:
Bank 1 for the O2 sensor is close to Cylinder #1
Bank 2 is close to cylinder #2.

That is how to figure out what side the codes for the O2 sensors refer to.
I was DUH on that one for a while.

hey rob, I would recommend an iCarsoft LRII for land rovers. It's a full service little reader that lets you read and clear DTCs. It lets you get freeze frame and live stream data which is pretty useful. The best part is it's only $175ish.
http://www.roverparts.com/Parts/ILR-II

theres a good video about it. I just got it actually. I think you may be able tos hop around and find a bit cheaper, but I like to support those guys, they have a lot of good videos.

Oreillys sells Bosch OBD readers that work great with these trucks & the Bosch Motronic; varying models from around $70 and up.
The OBD1100 has freeze frame, live data on all systems, emissions readiness on all systems, ABS, etc for under $100. It shows function on all 4 Oxygen sensors & will quickly tell you which are registering.
The plug wires on these trucks go bad all the time because underhood temps are extreme. Check each wire at the boot, espc #5. Sometimes it will just split apart right there & you find an easy fix. Your problem may lie in old, faulty equipment.
If plugs & wires are that old, the PCV hoses/filters surely need replacing so don't overlook that. Synthetic oils not the way to go in these old fashion power plants...use the heaviest Dino oil on the shelf; those designed for Diesel engines to be exact, 15w-40