Hi, guys and gals.... just want to make a question... to be sure...maybe is a silly question..

Question.... Is this the left rear or drivers side rear sensor?

Some history....
I have reading the p0140 and p0141 codes... bank 1 sensor 2...I have been reseting the codes but appears again... at mornings when the truck is cold every day... and some times during day....I travel with the code reader always, to reset the codes...jaja
today I noticed, at a stop light, the truck suddenly, rpm goes down to zero and the back again to normal... around 600 ... and the check engine lights immediatly... the codes appears again..

another question....Does this o2 sensor can cause this rpm variation??

thanks for your time...

Regards...

 

No, you have something else going on. I'd suspect an electrical problem, the O2 sensors provide data to the PCM to adjust fuel mixture (slightly). and unless you have a RHD Rover the left rear is the Drivers rear (bank 1 is the left side)

 

I'll second the electrical bug... check the rear main harness that rides the top of the firewall going to the passenger side port to behind the glovebox. When I got my disco I had a myriad of intermittent sensor problems that seemed almost random. I opened up the palstic T shapped clamp that connects where the o2 wires run up to meet that main harness and there were a bunch of wires that where either crimped or fraying and grounding or shorting out on each other depending on how and when they rubbed during stopping, bumps, turns etc. Also check the harnesses themsleves, especially with the o2's as the wires have 2 hazards... contact with the exhuast pipes and dripping oil from leak prone valve cover gaskets. Also double check all the ground connections in the engine compartment along with the battery terminals, they might be loose or corrorded or covered in road crap.

 

ps. bank 1 is almost always drivers side, bank 2 passenger side.... sensor 1 precat, sensor 2 post cat.

 

I got the correct position... and here is an update.... I change the o2 sensor and reset the fault codes p0140 and p0141.. and finally goes away......

Now... the disco runs good but after a few minutes on the road and make a stop the rpm fail appears again... rpm down and back to normal... check engine .... on again.....

new code.... p0440 I think.. don't remember right now... but it is someone related to the evap system..... I'll check it and confirm it...

and... for the electrical "T" cover/connector.. I going to check too..

Thanks for your help and comments....

 

When you get confused, use
http://enginecodemaster.com

That is what http://enginecodemaster.com is for!

As a rule the BANK matches the cylinder of the engine for the side the sensor is on.

Bank 1 - cylinder 1 side.

Bank 2 - cylinder 2 side.

Sensors can short internally or go open.
Just replace them and don't guess the wiring.

Yes, a sensor going on and off - can mess with idle speed as the engine will be
trying to go from closed loop to open loop.

Best to get a code scanner that shows LIVE data and watch the sensors.

 

Thanks...Excellent Information,,,,

And by the way ... confirmed ... the new code is p0440 Evaporative System ......

I going to make a research thru the forum and see what can I do to fixed.... and of course if any one has an idea.. is welcomed......

Thanks a lot...

 

Just for info....I read,,, read again,,,, and after a while... the Purge Valve was the suspect bad one... so ...I take a chance and do it a clean with throttle body cleaner....

Since the clean.. my Disco runs great and do not fail in idle.. not any more... no codes and no three amigos...... great....

Thanks to all., see you later.. I'll be around...maybe with another silly question....