1. yes, not to be confused with the sensor for the temp gauge.
2. Sounds about the right place. I could out and look, but it's dark outside and cold..
Last one I replaced was on a GEMS engine and easy to get to.
3. test while in.

 

The O2 sensors on most cars simply vary in voltage depending on the exhaust moving past it - if your ECU is throwing - "front o2 sensors NO activity" then that usually means the ECU is not seeing the variance in voltage it is expecting when polled. So check everything up to the ECU.

If you can find someone with a good scan tool, you should be able to see the O2 sensor values... if the values are not varying, probably no need to worry about anything else.

A good shop manual should also have the voltage and resistance values to be expected from a idle 02 sensor... but you'd need a scope to truly test independently from the ECU... so just do what you can. Verify up to the ECU that all looks good.

You could also have two batches of faulty O2 sensors... but doubtful.

 

Well, I got around to pulling the ECT sensor plug and at cold it tested at 2.12 @ 20k OHMS. Someone said it should read around 300 ohms at warm...does that mean I need to warm the truck up and then test the sensor or plug while in? How do I test the sensor while warm and in the inlet manifold?


Would have been nice to get this done earlier, but I did manage to replace my original upper radiator hose with a "newer style" one and shore up the connections to my alternator.

 

Since you have it out, try putting it in a pan of hot water.

 

Did they tell you what that fuse does? mine blew i replaced it and now the car runs for 30 seconds and shuts off???

 

They didn't explain what the fuse did. My mechanic told me what it has something to do with the ERG. I had taken the car to the L.R. dealer, A&L in Monroeville, to have them program a new(Used) ECU for my car because it was running rich. This is after putting a new(rebuilt) engine in replacing almost everything over the last year. They did the programing with adaptations but said that it still was running poorly, they said they did some more test, $300 worth, and found the bad fuse. On the good side I'm now getting around 14 MPG when I was only getting 8 or 9 prior. On the other side I'm not convinced that in reality the extra $300 of test and the one bad fuse were the problem.

 

FWIU fuse 2 powers almost all the emissions equipment including o2 sensors

The Rover should "work" without it, but it will run in open loop mode safely making sure it doesn't run lean by running it rich

A scanner may reveal a code due to some part not working (EGR, O2 Sensors etc.) and a wrench monkey may spend money replacing that one part 5 times and eventually the ECU and what not... but yeah... but with no power, that part is dead. Even when its new.

And really the computer said that and Rover dealer with a good rover trained mechanic should know through procedure how to interpret and properly diagnose simply and almost instantly.

A bad fuse usually means something shorted... you might want to double check wiring harnesses for busted conduit and pinches, exposed connectors without dielectric grease etc.

 

If the fuse powers the O2 sensors, it only provides power for the Heating Element within the sensor. Once the sensors gets up to operating temp (600deg) it will provide a signal and the ECM will go into closed loop. The heater allows this to happen sooner, within 90 seconds or so.
You can test the O2 sensor with a volt meter. Identify the signal wire and it should produce a voltage UP TO 1V. As 1V = Rich, it will cycle down to close to 0V, and back up again. If the heater is working, you can turn the key-on (engine-off) and see the signal slowly respond as the sensor heats up.

 

Bingo. I finally found this info myself.
My truck is running in open loop and my front o2 sensors have NO ACTIVITY. The live data I read this morning supported this, as they were stagnant at the default 450 set by the ECM with no movement at all, cold, warm, hot, etc. It continued to run in open loop. It is my understanding that if the ECM does not get communication from the heater then it will run the truck in open loop and won't let it go into closed loop even when at operating temp.

Now this leads me to your suggestion of testing the heater. I have a multimeter but have only used it (ever) once. Can you explain how to test the signal wire for dummies? Have the multimeter set to _, touch the _ to the signal wire, and the other _ to....?

I really think its my heaters now, and after talking to several master tech's who have mostly never seen the ECM be the cause, i'm pretty confident too.

Thanks!

 

Do you have an engine code for O2 heater? If not, the ECM won't know to keep it in a fail-safe condition and not go to Closed-Loop. Do you have RAVE?