P0130-p0150 and strong gas smell from exhaust after welding exhaust flange

robertofollia

Well-known member
Aug 3, 2005
548
1
My home is where my Disco is
Dear all,
D2, 5 speed, V8 (yes, it exists). Feb'2021 broke right side exhaust flange from Y pipe
Only has pre-cat O2 sensors
Had been code free for the last 15 years.
Disconnected O2 sensor connectors with utmost care. Sprayed them with contact cleaner.
After undoing rest of fixings, Y pipe fell on the floor with a loud bang (no more than 2 inches distance)
Welder welded and reinforced exhaust flange but weld was performed with both O2 sensors fitted (i did not like that)
Now idle is good, performance is low, fuel consumption is higher (but in the last 120 miles has gone better) , fuel smell in exhaust and P0130 and P0150 (O2 sensor circuit). Connectors are OK.
Oh, by the way, no CEL (Euro spec D2 don't light CEL so often)
Might have both O2 sensors died because of the fall of Y-pipe and weld?
Bur remember 15 years ago when MAF died I got the following codes
Testbook results:
P0150 and P0130- O2 sensors
P0171 Adaptative fuel mixture control Bank 1
P0174 Adaptative fuel mixture control Bank 2
too lean!
All vanished after new MAF.
Best regards
 
Last edited:

robertofollia

Well-known member
Aug 3, 2005
548
1
My home is where my Disco is
Bump,
test drive yesterday. Performance improved a lot, gas mileage as well. Disconnecting battery to reset values helped a lot.
But.... after some minutes driving the fault is back P0150 and P0130- O2 sensors circuit...
When clearing codes, at first, when warming up, both 02 sensors read, at idle and when using gas pedal. On the overrun they read 0 (usual at in the overrun the mixture is lean). But after 5 minutes and fully warmed engine both o2's voltage drops to 0v, guess it's ecu throwing code.
Idle is perfect and have found no leaks. So... bad sensor, bad wiring, or bad ecu?
Bad sensor could be, as they are 22 yrs and 130K miles old. But getting even a genuine Bosch one seems to be a hit and miss russian roulette.
 

discostew

Well-known member
Sep 14, 2010
6,502
525
Northern Illinois
You need to check the ground side of all the sensors. Black/Red wire that goes to each sensor. I'm guessing either a terminal is backed out of one of those connectors, or the ECM is not grounding those wires.
 

robertofollia

Well-known member
Aug 3, 2005
548
1
My home is where my Disco is
Hi all, thank you. I mean, I checked grounds and are ok, Terminals checked and are ok. Sensors do read voltage, only on the overrun read 0 V), but at aidle and when warming up they do read voltage, don't have the numbers here, should check again. Only after 2-3 miles voltage drops to 0 and ECU throws the code. Best regards
 

robertofollia

Well-known member
Aug 3, 2005
548
1
My home is where my Disco is
Update, Once codes cleared
-Hot or cold. Engine off, OBDII on, O2 sensor output voltage reads 0,445 v both banks
-After start up, drops in both banks to 0,385
-When sensors start to heat up with exhaust temp bank 1 drops to a lower value than bank 2
-After 1 minute bank 1 drops to almost 0 (o,015 v) but bank 2 stays around 0,25 V
-On the overrun both banks drop to 0., Bank 2 recovers but bank1 stays in 0. Bank 2 reads around 0,015-0,020V
-After 5 minutes both read 0 and throw the code
Guess it's knackered O2 sensors. Replacements ordered.
Best regards
 

robertofollia

Well-known member
Aug 3, 2005
548
1
My home is where my Disco is
Update,
Sensors changed. Old ones were easily removed
Once codes cleared
-Hot or cold. Key on Engine off, OBDII on, O2 sensor output voltage reads 0,445 v both banks
-After start up, drops in both banks to 0,385
-When sensors start to heat up with exhaust temp bank 1 drops to a lower value than bank 2
-After 1 minute bank 1 drops to almost 0 (o,015 v) but bank 2 stays around 0,25 V
-On the overrun both banks drop to 0., Bank 2 recovers but bank1 stays in 0. Bank 2 reads around 0,015-0,020V
-After 5 minutes both read 0
If I stop engine, clear codes, they still read 0 after startup, then bank 2 recovers and reads, quite low but reads and reacts to gas pedal position. Stays ok for around 20-25 minutes, then reads 0
I guess it's not connectors but wires dead, but..... does anyone sell these harness components separately, does LR list them? and guess it's a PITA to remove as the wiring seems to go under inlet manifold...

Best regards
 

simondewing

Well-known member
Feb 10, 2020
54
11
Texas
As you are reading voltage's from the O2 sensors which are changing very unlikely to be a wiring issue.
Sounds more like your ECU has an issue (or you have a leaky injector) and it is dumping way too much fuel in causing the whole thing to run rich (which the o2 sensors are correctly reporting) just the feedback loop is not managing to lean the mixture to correct.
What are the fuel trim values?
 

robertofollia

Well-known member
Aug 3, 2005
548
1
My home is where my Disco is
Hi Simon, thank you for reply, codes are the same, P0130-P0150.
Don't know if it is a leaking injector. Codes cleared, runs rich if you stand close to tailpipe.
After several miles driving performance returns to normal levels and exhaust smell is close to normal. Then there are no "new" codes but "pending" codes, which happen to be the same (P0130-P0150). If I clear them and reset car, Key onn engine off read "0"
I think it might be ground wire toast. Will have to check continuity. Only have to guess where the junction is (Think on the back of the "vee", close to the coil packs, thank you, Land Rover., for making everything sooo easy..)
I mean, Key on engine off, cold or just 2 miles driving after startup, as soon as O2 begin to read 0, codes cleared, voltage is 0,445 V each sensor.
Engine hot after a lot of time driving. Stop. Clear codes, reset. Key on engine off: voltage is 0. Start up and continue at "0", sometimes bank 2 recovers, but bank remains 0
Knew there had been issues with a connector placed behind/besides coolant expansion bottle, but can't ascertain which of the three of them
Pretty sure there are no exhaust leaks nor intake leaks, but will test again in 1 week as I would set fire to the Disco otherwise as this year It has been more time off the road than on it.
Best regards
Best regards
 

simondewing

Well-known member
Feb 10, 2020
54
11
Texas
Sorry my bad, I wrote last message while drinking first coffee of the day!

High voltage from the o2 = rich, low voltage lean, so its sensing lean and widening the injector pulse hence your over fueling.

I guess welding may have cooked the wiring or ecu.

Suggest disconnecting the sensors at the plug and using a multi-meter to check continuity back to the ecu connector.
There is a ground connector from the back of the head on the left side (drivers side in North America) to the bulkhead (firewall) check this was not burnt out but its not the only engine ground connection.

Don't have the wiring diagram in front of me but I believe the O2 ground may be to the ecu then through the ecu ground.
 

robertofollia

Well-known member
Aug 3, 2005
548
1
My home is where my Disco is
Hi, Simon, thanks for reply,
this is what will do.
I guess the ground wire from both sensors is cooked, because:
- Key on engine off, cold, or just 1 mile driving, codes cleared=0.445 V both banks
- Key on engine off, hot, or just 1 mile driving, codes cleared=0.00 V
Will disconnect both O2 sensors, then check continuity in connector (which will be quite bad, as in D3-LR3 fuel level gauge wires), then splice wiring and renew that part of harness. Problem is don't know where the joining to the ECU is, because both O2 harnesses climb to valve covers and seem to disappear under inlet manifold.
Found this link with very good detailed info:
But will take my time, as before I have to do routine maintenance to brother's LR3 (complete fluid change, engine, tranny, diffs, t/box, brakes and coolant, plus brake pads, plus tranny sump plus mechatronics sleeve.....)

Besides, There was a post here
in which pdxrvermech stated that
"theres a grey plug connection (10 or so wires) back by your coolant reservoir, close to the firewall. Unplug it and see if you have any burn spots on it. Ive ran into it a couple times."

I've seen it but have been unable to umplug it, seems welded....

Best regards
P.S. My D2 is Euro spec (LHD) 5 sp manual V8 so that means that mostly all P0XXX codes do not switch check engine light (CEL) on, you have to guess by plugging the code reader in.
 

simondewing

Well-known member
Feb 10, 2020
54
11
Texas
Grey connector sounds like the connector from the transmission wiring up to the ecu,
Only issue I have had with that was a CAN bus error when it could not see the TCU.
Not sure if the downstream O2 sensors go through there on US spec (I never checked) but upstream sensors (which are all you have) go into the engine wiring harness which goes through the bulkhead on the passenger side and plugs into the ecu.
Can't remember the pins on that but there is a wiring diagram in Rave that should guide you and has all the grounding points as well.
The diagrams are for all the different models so you should find what you need.
If you have "scrap" O2 sensors it helps to cut the connectors off with a wire tail and use them for testing.
Then just need a long lead with a couple of crocodile clips and a meter.
Nearly all of the O2 sensors issues I have had have been corrosion at the connectors under the car (on the ecu side) and fixed by replacing the pins in the connectors there.
Sounds like your welder may have fried the wires back to the ecu though.
You could always try and find a replacement engine harness and just replace it all
 

robertofollia

Well-known member
Aug 3, 2005
548
1
My home is where my Disco is
Hi Simon, thank you so much, will take a look ASAP and of course will post results here in order to help anyone else with this nightmare O2 codes.
1st will check pin continuity and grounds and will clean terminals and let them dry. Will try again.
After that will take out O2 harness (upstream, as only have that) and check and replace, one by one.
Will test again and if all is ok, perfect, if not may set fire to the truck (this year, besides exhaust, roof retrimming, PAS pump went bust, pas cooler went bust, new fuel pump and something else I might have forgotten...),,,
Best regards
 

robertofollia

Well-known member
Aug 3, 2005
548
1
My home is where my Disco is
Well, finaly back after having my worshop occupied by my brother's LR3 (disco 3 v8), collected last sunday so had time today, almost 2 months later, to work in my truck
It's weird, have not done anything during these weeks (I had been dealing with LR3 all oil changes, incl trranny and axles, brake bleeding, mechatronics sleeve+gearbox sump + coolant and brake fluid change).
Now for Disco 2:
Before starting checked codes cleared and selected Short fuel trim and O2 voltage sensor 1 (mine has downstream, only pre-cat sensors as it's euro spec 1st build from 1998). voltage 0,445 V. OK
did a 9 mile test. Before (untlil last time used, mid august), sensors would stop reading(1st bank 2, later bank 1), after 2-3 miles and throw the code.
Today did not stop reading at any moment, only 0,00 on the overrun (mine has manual tranny), but read normally as soon as the gas pedal was touched
But what puzzled more was bank 2 short fuel trim. At idle is oscillated randomly between 0%, 25% with no mid values.
Sensors were reading all time, but bank 2 showed a lower voltage, around 0,1 volts less (eg bank 1 0,4 V, then bank 2 0,3, so richer).
Overrun and accelerating short fuel trim 0%
Bank 1 short fuel trim stayed all test 0%
Bank 2 0% driving except at idle, switching between 0%, and 25% and sometimes -14%.
So guess I've got a random intake air leak.
Being a V8 I guess leak could be where manifold volts to the "vee", because otherwise, being a V8 engine, would affect both banks.
Will check bolts and studs for tightnesss tomorrow, test it again and come back with the results.
or might be that fuel trims (bank 2) are still adapting after the february ride with no bank 2 downpipe which might have pushed trims upwards in a huge way?

But why 2 mmothns ago sensors would stop reading after a 5 minute drive and throw the code, and today no codes, and did not stop reading, behaving normally? Have not doe anything, the car simply stood unused while my worshop was occupied by my brother's LR3.
Best regards
 

rovercanus

Well-known member
Apr 24, 2004
9,485
158
Check your fuel injector o-rings. They can give lean codes and cause general shittyness while driving.
 

robertofollia

Well-known member
Aug 3, 2005
548
1
My home is where my Disco is
Hi thank you all for input. Fuse 15 is OK. Today i just discovered one bolt which could be tighter. It was one that linked plenum chamber to bank 2 upper inlet manifold, just above alternator, maybe that one caused vacuum leak. Did not have time to perform a test drive with the scan tool connected. Will get some carb cleaner to spray on the outside part of plenum and manifold to see if engine speed varies even the tiniest bit.
Performance is OK, and idle is smooth as oiled spaghetti
Everything was renewed in 2009 when HG job was done, but guess int these 12 years o rings might have gone bad with E10 we have around.
Will do a test again and if there is no short term fuel trim fluctuation, will consider issue solved. Otherwise, will go for injector o-rings, which are far easier to change than the **** valley gasket, this is a pita to change.
By the way, is there any better alternative to OEM or gen-you-win? I mean in terms of reliability and long service.
Best regards
Robert
 

rovercanus

Well-known member
Apr 24, 2004
9,485
158
Check on ebay. There are a couple of businesses there that sell refurbished injectors. Make sure to lube the o-rings before you insert them.