O2 heater circuit

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Discovery 2004 v8 auto

My eml came on some time ago and i read the fault codes and got p0141 & p0161 heater circuit either bank sensor 2, changed the o2 sensors for new ones that was fine for about 40 miles then eml came back on. I have replaced the o2 sensors again for new ones and 20 miles on i get same eml on and same codes. I have checked the wiring where exposed with nothing obvious, and as it is both downstream o2 s i cant imagine i have been that unlucky to get 4 faulty lambda sensors.
Is there anyone else that has come accros this fault with any joy fixing it?
And are they really needed as p38 with same engine doesnt have them.

Did you handled them with care and torque them to exactly the recommended values(45 Nm /33 lbf.ft).)?, it's important especially if they are not Genuine

EMISSION CONTROL - V8; DESCRIPTION AND OPERATION 17-2-13 said:

CAUTION: HO2 sensors are easily damaged by dropping, over torquing, excessive heat or contamination.
Care must be taken not to damage the sensor housing or tip.

Click to expand...

Ye handled carefully and did them up not to tight as was using a 22mm spanner. They are working fine its just the heater circuits that arent

Have a close look at the engine ECU connector and pins.

The 12-0V heater circuits are generated by the ECU, so you may have a bad connection on the plug and pins. The ECU's are pretty well made, but that's not to say you couldn't have a faulty one.

The 0-5V sensing connections are in the same connector C0635.


Peter

Would it not be strange to have 2 faulty pins that do the same job?

I will check the pins and all help is much appreciated!

Plus and pins ok.

Connected a fault code reader and looked at voltage output for both sensor 2s (post cat) on both banks os about 0.45V.
However the sensor 1s (precat) were switching all the time between 0.1 and 0.9V?
Is this usual?

The readings will toggle when the system is working correctly, range of values will depend on the Lambda type, operating temperature etc.

As it's a closed loop system, it is cause and effect, the ECU is adjusting values and reacting to mixture changes as detected by the Lambdas.

Do you have two or four Lambda sensors?

Peter

Hi peter car has 4

So are we talking about pre or post cat sensors?

Peter

Post cat bank# sensor 2