[mcaslan]

2 Questions on my 2004 Discovery 2 w/ 89000miles - would welcome advise as thoughts range from the inexpensive to expensive. Mechanic has replaced
4 - O2 sensors
MAF
Smoke tested

1 - Been battling the following codes after cleaning O2 connections. P0150: P0174: P1174:
b - Cleaned connectors with contact cleaner
c - See Voltage of O2 sensors. When starting car all voltages rise to .5volts. Then B1S1 and B2S2 begin to operate 'normally' swing from 0 to .9 v. B2S1 and B1S2 voltage drops slowly to 0volts over 30 seconds.
d - mechanic did a smoke test and found a leak at Intake Manifold area

2 - What is this open ended hose and what impact left like this does it have?

Am I right in position
Bank 1 Sensor 1 = US Drivers Front
Bank 1 Sensor 2 = US Drivers Rear
Bank 2 Sensor 1 = US Passengers Front
Bank 2 Sensor 2 = US Passengers Rear

Vehicle VIN: SALTL...
Vehicle Manufacturer: Rover
Vehicle Calibration ID: Not present

Current Fault Log
------------------
P0150: O2 Sensor Circuit (Bank 2 Sensor 1)

Pending Fault Log
------------------
P0174: System too Lean (Bank 2)
P1174: [BMW] Fuel Trim Adaptation Additve Bank 1 Malfunction

Historic Fault Log
------------------
ECU reports no historic faults
Other discovered fault codes
(possibly pending, current or manufacturer specific)
----------------------------------------------------
ECU reports no other fault codes logged

End of report.

 

[redtruck12]

Not too sure on the diagnostics but that hose looks like a differential vent tube ? in your picture

 

[Disco Mike]

The hose is fine, have you checked to make sure your front 02 sensor connection are not full of oil? Have the front 02's ever been replaced if not, it is time which will clear the 174 and 1174 codes.

 

[mcaslan]

Replaced O2 and cleaned connections

I am posting and am receiving the codes after doing the following noted in original post.

Mechanic has replaced 4 - O2 sensors
Been battling the following codes after cleaning O2 connections. P0150: P0174: P1174:
Cleaned connectors with contact cleaner

Any revised thoughts?

 

[redtruck12]

I would agree with mike
Oil contamination in the front o2 sensor electrical connectors or possible poor contact at the o2 sensor connectors ( I would suspect drivers side upstream o2 connector as it is a pain to get your hands on and in an area prone to oil contamination)
As for the hose there should not be anything connected to the end of that plastic tube / hose in your picture

 

[mcaslan]

Agreed it is a very awkward area.

I used contact cleaner with thin red tube attachment. Also had a 5 gal air tank with high pressure nozzle to blow air and oil out. Repeated process a few times and in the connector housings.

What I find most interesting is that when the car is started 1st thing the O2 sensors act normally volt going 0 to .8 volts even swings. After half a minute the range that O2 in position 2-1 starts to diminish range 0 to .7volts then 0 to .5volts down to 0 volts over maybe 2 mins.

I'm trying to balance the idea of faulty wiring, connections versus the comment that on smoke test they found a leak on Intake Manifold.

So is the diminishing voltage range an indication of lean due to Vehicle warming up and engine management adjusting the mixture - or faulty new O2 sensor / wiring.

May sound a pain to keep reiterating the question but many of the symptoms were in my original post and answers referred to things I had already included.

 

[Disco Mike]

You may in fact just have a failed 02 sensor, won't be the first one to die an early death. You have a one year warranty so go get it replaced.

 

[redtruck12]

My advice
If you are confident that it is not a connection fault and they were goos quality o2 sensors that you are also confident are not cheap/ universal ones, go after what you know before chasing ghosts of speculating on a high tech mystery fault.
From my experience that type of fault is rare.
You state that you have a known intake leak....
One of the most critical computer inputs for fuel strategy is upstream 02 readings
If 02 sensor tell the computer it is lean ( abundance of fuel) the strategy will be less fuel and vice versa for 02 rich.
A vacuum leak of any kind including a manifold leak will screw stuff up and set codes
I would start with what you know and deal with the intake leak

 

[Disco Mike]

In this case though he is not getting a bad fault code for that 02, it is completely dead per the 150 code.

 

[redtruck12]

Still trying to get my around why both diminish as the vehicle runs ( o-.7 then 0 - .5 then 0 volts over a 2 minute period ) and has a known / diagnosed vacuum leak

 

[Disco Mike]

Humor me, a 150 code is a dead not ailing 02 sensor, is not effected bu a vacuum leak and needs to be replaced.

 

[mcaslan]

I'm going to post the end of thread in a couple of threads to close them out as resolved.

Early October the Discovery stopped and wouldn't restart for 45 minutes. Had it Serviced and we tackled...

1) Front Right (passenger) O2 sensor
2) New CPS
3) New Transmission Park solonoid (kept blowing fuse)

Car and engine are running best they have in a long time.