i, the saga of the "free" D2 continues.

My son got it running after a total teardown/rebuild for a slipped sleeve (he was given the D2 for free, I have about $2,700 in parts for the rebuild). After driving it about 1000 miles with NO issues (including a 400+ mile RT to Dallas), it has since had a persistent P0150, followed by P0174 code (about a week).

First, I tried cleaning residual pre-rebuild oil out of the connector. Then I replaced the Bank 2, Sensor 1 (OEM Bosch). Still generating those codes.

Did the old "squirt starter fluid" around vacuum, PCV, etc. hoses, injectors, intake gaskets, etc. Actually found a leak at where the throttle plenum bolts to the upper intake plenum (my son forgot to torque one of the bolts -- the one under the throttle body for the plenum for bank 2). Torqued it to spec but still generating a P0150/P0174 code combo.

Have a Elm327 bluetooth ODBII that works with the TorquePro app on my phone (had it for 6 months, finally got it to connect with my phone), but don't really know what to start measuring.

So does anyone have the definitive list of steps one should take to troubleshoot the infamous P0150 gremlin?

Let me start one here and hopefully folks will pile on, re-prioritize, etc.:

1. Check Bank 2 Sensor 1 connector for oil ; clean connector and fill with dielectric
2. Check Bank 2 for air leaks (intake and vacuum) using starter fluid technique (I have an 18 inch red spray straw I bought on an aircraft equipment site -- it has been a priceless tool for this kind of thing): check at throttle-to-upper plenum gasket (the one under the throttle as that feeds intake Bank 2), upper plenum-to-intake gasket, camshaft valley gasket (bank 2/passenger side intakes and valley end gaskets)
3. Replace Bank 2 upstream O2 sensor
4, Inspect Bank 2 plugs and if needed replace all (what does their condition tell you about the underlying situation?)
5. Clean injectors (spend money and spring for the BG injector cleaning service from a shop -- direct injection)
6. Test wires from connector to ECM (ODBII data be used to do the same, right, i.e., if you are getting voltage readings from the Bank 2 Sensor 1, then the wire continuity is by definition OK, right?)

I am guessing that there are probably about 12 more steps here that people are aware of -- smoke test, testbook (whatever that is), take to a LR expert mechanic, give up -- etc.

Looking forward to all the input.

AustinDiscoveryBill

 

i have the p0150 and believe i have to re wire my harness for the sensor, replaced the sensor three times and even used one from the other side and still had no voltage readout.

 

OK, in playing with my bluetooth ODBII (Elm 327 and Torque android app), I managed to pull voltage data over time for my upstream Bank 1 and Bank 2 sensors (see attached).

The Bank 1 sensor behaves as what I suspect would be "normal": it bounces from 0.1 to 0.9 volts every second or so as it adjusts the air/fuel mixture.

In contrast, my bank 2 sensor began at 0.9 volts at startup and then the voltage just keeps dropping, bottoming out at <0.1 volts and never never recovering. (I only captured the last 10 recorded seconds or so -- not sure why)/

Is this what it means to for the metering system to go "open loop"?

I assume that this tells me that a) this sensor and its wiring is working fine, and b) something is causing Bank 2 to lean out. Does this definitively point to an air leak (an air leak would lean out the mixture, right?) or could something else be causing this (a bad O2 sensor even though it's new, a problem with the ECM, etc.?)

Some naive thoughts about what else it might be that would introduce excess air/O2 into the exhaust (since I've tested the intake already and found my one leak):

1. A stuck open or otherwise malfunctioning SAI air injector valve on bank 2 (would this throw some other kind of LR D2 specific code?)
2. a leaking head-to-manifold gasket (but you would expect to hear that, wouldn't you?)
3. A leaking manifold-to-exhaust gasket (again you should expect to hear something like that, right?)
4. a sticking exhaust valve?
5. a sticking or clogged injector or even Bank 2 fuel rail?
6. Something else?

Insight from any of the engine management experts out there would be greatly appreciated.

AustinLandRoverBill

 

Sorry to hear about your wiring harness.

I don't think that's my problem as I am getting up to the full 0.9 volts out of my Bank 1 upstream sensor, but it drops to 0 within about a minute and a half. 0 volts is an open loop right?

I can't believe that the new 02 sensor was defective from the factory.

And if it were an air leak, wouldn't it go open loop a lot faster? Or could a small air leak cause this?

Any idea what could be the root cause this kind of voltage behavior?

 

Sorry to hear about your wiring harness.

I don't think that's my problem as I am getting up to the full 0.9 volts out of my Bank 1 upstream sensor, but it drops to 0 within about a minute and a half. 0 volts is an open loop right?

I can't believe that the new 02 sensor was defective from the factory.

And if it were an air leak, wouldn't it go open loop a lot faster? Or could a small air leak cause this?

Any idea what could be the root cause this kind of voltage behavior?

 

Problem

Code: P0150 Bank 2 Sensor 1 (B2S1) Circuit Failure, Followed a short time later by a P0174 lean condition code.

Observations and Other Data:

The measured B2S1 voltage begins at 0.9v at startup, drops to <0.1v after about a minute-and-a-half. The B1S1 sensor has the expected voltage profile (going from 0.1 to 0.9v then flipping, every one second or so).

Engine otherwise runs fine. No rough idling, hesitation or other behavior or sounds.

Engine was rebuilt up from a bare block (slipped sleeve repair) and driven about 1,000 miles before this problem appeared.

B2S1 has been replaced with OEM Bosch “orange connector” sensor (proper one for the upstream)

Diagnostic Decision Tree

First Diagnostic Question: Is it 1) a bad O2 sensor/sensor circuit or 2) is it a lean condition that is causing the trouble codes and subsequent voltage behavior of the B2S1.

1. If it is a bad O2 sensor or sensor circuit:

a) Wiring isn’t likely to be bad as the sensor does show voltages within the expected range (0.9-0.1v) and voltage changes?

b) Could the ECM be bad? Would the ECM go bad for just one sensor and not all of them, especially as they are all on the same ECM connector?

c) Would the voltage profile over time of sensor indicate some type of failure: the sensor, the heater, something else?

d) If the Bank 1 was going into an “open loop” state, i.e., rich mixture by default, wouldn’t the sensor – if it was working correctly – show a persistently high voltage, not a persistently low voltage?

2. If the sensor and circuit are working correctly and therefore are not the source of the P0150/P0174 codes, then what could cause a lean condition, i.e., a high Air:Fuel ratio, a) too little fuel or b) too much air?

a) Too little fuel: what could cause this?

i. Low fuel pressure (fuel pump, fuel filter, pressure regulator): Unlikely, as low fuel pressure would be affect both banks

ii. Bank 2 Fuel Rail: Is it possible for one rail to get clogged up with something and not the other? How to test?

iii. One or more injectors stuck closed: if the ECM was malfunctioning, woudn’t this throw a code? Would the vehicle run rough/poorly (which it doesn’t)? Could a sticking/stuck/clogged injector be diagnosed by looking at the plugs? The plug on a lean running cylinder would be white, correct?
iv. Sticking intake or exhaust valve: Not sure what a sticking valve is or would do

b) Too much air: what could cause this?

i. Faulty ECU: Only way for an ECU issue to affect just one bank would be thru the injectors (right?); if injector management was faulty, isn’t there a trouble code for that that would be getting generated as well?

ii. Faulty MAF Sensor: Unlikely as this would cause too much air going to both Banks, not just one

iii. Throttle Gasket Leak: Unlikely as this would cause too much air going to both Banks, not just one

iv. Idle Air Control Valve (IACT): This does have two feeds to the throttle plenum on the Disco 4.6, however wouldn’t the idle be affected if there were a problem here (the vehicle idles fine?

v. Vacuum Leak: Unlikely as the vacuum is drawn from the throttle-to-intake plenum which serves both Banks, and a leak here would therefore cause too much air going to both Banks, not just one.

vi. PCV Leak: The Disco2 does have a PCV system that I do not totally understand – Bank 2 has a valve of some sort that “dumps” into the throttle plenum while Bank 1 “dumps” on the MAF side of the throttle body; however, given where they connect, as with a vacuum leak, wouldn’t a PCV problem affect both Banks, not just one?

vii. Throttle-to-Intake Plenum Gasket Leak: Possible, as there are separate paths – and therefore separate gaskets -- on the throttle plenum for Bank 1 and Bank 2. We ctually found that the plenum going to the Bank 2 intakes was not torqued to spec (identified using the spraying starter fluid technique and corrected that.

viii. Lower Intake Gasket Leak Somewhere on Bank 2 (along the valley gasket): Possible, tested each using the starter fluid method, nothing detected but am going to buy another can of starter fluid and test again

ix. Rocker Cover Gasket Leak: There is a little oil dampness (very little) around the Bank 2 Rocker Cover gasket (the Bank 1 Rocker Cover gasket is completely dry), but how would a leaking Rocker Cover gasket affect the intake as the two are isolated from one another?

x. Leaking Injector-to-Intake O-Ring: tested using the starter fluid technique, no obvious leak on any of the Bank 2 injectors but will test again

xi. One or More Stuck Intake/Exhaust Gaskets: Not sure what the mechanism here would be that would cause a lean condition, but adding it anyway. Wouldn’t the effect of a stuck/burned valve show up on the spark plugs?

xii. Leaking Supplemental Air Injection (SAI) Control Valve: There is a valve for each bank so it is possible that the Bank 2 SAI control valve is faulty while the Bank 1 valve is working properly. Would a “stuck open” SAI control valve allow enough air into the exhaust ports on Bank 2 (even when the SAI pump is not running) to create a lean condition to be measured in the exhaust gases?

xiii. Leaking Exhaust Manifold Gasket: Nothing obvious, every manifold bolt has been retorqued, don’t hear anything that would indicate a leak

xiv. Leaking Exhaust Manifold to Downpipe Gasket: Nothing obvious, every manifold-to-downpipe nuts has been retorqued,, don’t hear anything that would indicate a leak

 

Hello, any ending to this story? I have P0150 followed by P0174. i'm thinking something to do with wiring from engine to sensor. i've tried 3 different sensors and always get the same result.

 

Boy that was a lifetime ago.

I think it turned out to be the purge valve.

There are a bunch of threads about it, how the LR OEM part is outrageously expensive and how there is a Hyundai equivalent part.

I bought the aftermarket Hyundai part at an Autozone but after a few days the codes were back, so I went and found a genuine Hyundai part (with the stylized "H" on it) on Amazon for a lot cheaper ($25 versus $40 for the Autozone aftermarket as I recall) and it has worked fins since.

I think I posted that experience, so check all my threads and you should find it.

Very easy to replace. Good luck.

 

Hello all,

I seem to have the opposite problem than most here in this thread. I purchased some new FOBs which arrived only with the 15-digit codes /barcodes, and no 6 digit code sticker on the PCB. I have a Nanocom which takes the 6-digit codes for FOB programming.
Does anyone know how to translate the 15 digits into 6 digits?

Thank you
Sutherland