V8 O2 Lambda sensor - changed but EML back on?

markyzs180 · Feb 10, 2017

Evening... 03 plate Disco 2 4.0 V8 LPG conversion... so, just before Xmas, eml light on, check codes 'Bank 2 pre cat lambda sensor' ordered one (non genuine but bosch) finally got it swapped out today (stripped the thread, re-tapped, fitted) ran like a dream for 5 miles then bam, eml light back on. Codes read and low and behold 'Bank 2 pre cat lambda sensor' grrrrrr.... so a couple of quick questions:
a) could some kind person confirm the part number of the sensor I need? (local dealer not playing the game)
b) just to allay my fears... bank 2 is the bank that has pot 2 at the front end ( LHS as you stand at the front of the car or drivers side if you're sitting in the car (RHD))

Thanks in advance....

sierrafery · Feb 10, 2017

What i know is that the original pre-cat sensors are not good anymore with LPG conversion read the description http://www.island-4x4.co.uk/oxygen-lambda-sensor-intermotor-mhk100920g-p-27663.html ... but my knowledge ends here

markyzs180 · Feb 11, 2017

Thanks sierrafery... hadn't seen that...got my icarsoft on it today and the livedata is showing no output which is what the old one was showing? So looks like I've wasted 45 quid on a replacement, destroyed the original one getting it out all for it to potentially be the harness! Further investigation requried...

markyzs180 · Mar 2, 2017

Managed to release the harness end of the connection from the mounting plate on the rear of the engine which was full of oil. Cleaned it all out with brake cleaner and contact cleaner but still nothing. Did a search and found someone else that had changed the sensor without cleaning the plug and had killed the sensor. So I've ordered another one! If this works I'll post up some pics/how to for us petrolheads as we seem to be few and very far between....

eightinavee · Mar 3, 2017

There is probably nothing wrong but a low air flow reading. The AFM MUST read 22-25 Kg/Hr at idle for the engine ecu to allow a wide enough injector pulse width. Below this reading and the engine can't get enough fuel to switch the sensor up to its rich reading - 0.8v.
Do a search on this,seems like I posted this many times in the past,thought all those V8's had been scrapped by now ! Not seen one in my workshop for several years.

markyzs180 · Mar 3, 2017

thanks eightinavee (like the handle!) there are just a few of us suckers left

I'll try and get a reading from the maf.... I've been reading the US sites and have read about maf/intake leaks but wanted to rule out what the diags are telling me first

... always liked Bath and its Roman heritage and Georgian architecture.... I really should spend a day there with the kids whilst a local expert takes a look at the beast ....

... how is your calendar looking?

R222RWD · Mar 5, 2017

Hey, not sure whether you got this fixed but I had exactly the same problem on mine. Kept putting it off as the thought of attempting to get the sensors out was so off putting, however two weeks ago the light has gone out, checked the codes no problems and running like a dream now. Might not be the case for you but I just gave it a good run. Good luck!

markyzs180 · Mar 5, 2017

R222RWD said:
Hey, not sure whether you got this fixed but I had exactly the same problem on mine. Kept putting it off as the thought of attempting to get the sensors out was so off putting, however two weeks ago the light has gone out, checked the codes no problems and running like a dream now. Might not be the case for you but I just gave it a good run. Good luck!

Thanks R222RWD and what is weird is the first time the light came on I was driving down to Aberdovey from Tywyn!!!
And funnily enough it did go out for a few days but came back

I've got a new Bosch sensor to drop in, was going to do it today but the rain asn't really stopped ...
Glad yours has sorted itself out and probably see you around Tywyn later in the year!!

R222RWD · Mar 5, 2017

markyzs180 said:
Thanks R222RWD and what is weird is the first time the light came on I was driving down to Aberdovey from Tywyn!!!
And funnily enough it did go out for a few days but came back
I've got a new Bosch sensor to drop in, was going to do it today but the rain asn't really stopped ...
Glad yours has sorted itself out and probably see you around Tywyn later in the year!!

That's really strange it happened down here! Hopefully mine will stay off, fingers crossed. Hope you manage to get it sorted as well. I'll keep an eye out for you later this year!

markyzs180 · Mar 5, 2017

I'm going to keep adding to this with bits I've done and things I've found as there's not a mass of info on the V8's so...

Got my meter out and checked the pins in the harness, these were taken with just the ignition on engine not running, readings were:
Pin 1 = Earth (from ECU)
Pin 2 = 0.45v (from ECU)
Pin 3 = 12v (From fuse box)
Pin 4 + 12v (from ECU - Heater circuit)
So that confirmed the ECU and wiring to the sensor is good.
I then connected the sensor and started reading the live data from the sensors as I started the engine... sensor 1 running as it should, fluctuating between 0.2 and 0.8v BUT sensor 2 (the problem one) showed 0.45v at start up and then dropped down to 0.0v ?
So I've got a new Bosch sensor which I will put in when it stops raining.
One thing I didn't do was check the MAF readings although I know it had a brand new genuine one fitted less than 8 months ago.
And I discovered that if you leave the sensor unplugged it stops the ecu from adjusting the fuel trim which has been at 1.50 and costing me a fortune!!

R222RWD · Mar 5, 2017

markyzs180 said:
I'm going to keep adding to this with bits I've done and things I've found as there's not a mass of info on the V8's so...

Got my meter out and checked the pins in the harness, these were taken with just the ignition on engine not running, readings were:
Pin 1 = Earth (from ECU)
Pin 2 = 0.45v (from ECU)
Pin 3 = 12v (From fuse box)
Pin 4 + 12v (from ECU - Heater circuit)
So that confirmed the ECU and wiring to the sensor is good.
I then connected the sensor and started reading the live data from the sensors as I started the engine... sensor 1 running as it should, fluctuating between 0.2 and 0.8v BUT sensor 2 (the problem one) showed 0.45v at start up and then dropped down to 0.0v ?
So I've got a new Bosch sensor which I will put in when it stops raining.
One thing I didn't do was check the MAF readings although I know it had a brand new genuine one fitted less than 8 months ago.
And I discovered that if you leave the sensor unplugged it stops the ecu from adjusting the fuel trim which has been at 1.50 and costing me a fortune!!

Yeah I found that too, loads of info from America on the v8's but not much from British forums. Out of interest what sort of mileage has yours done? Wondering if it's a standard thing at a set mileage they start to wear out - mines just shy of 125,000 miles.

Be interesting to see if the new sensor fixes it, I never considered the MAF when mine was playing up.

markyzs180 · Mar 5, 2017

R222RWD said:
Yeah I found that too, loads of info from America on the v8's but not much from British forums. Out of interest what sort of mileage has yours done? Wondering if it's a standard thing at a set mileage they start to wear out - mines just shy of 125,000 miles.

Be interesting to see if the new sensor fixes it, I never considered the MAF when mine was playing up.

90,000... running Zavoli LPG as well, not sure whether that kills them early? I keep hearing/reading 100k miles but not everyone is having them fail?

R222RWD · Mar 5, 2017

markyzs180 said:
90,000... running Zavoli LPG as well, not sure whether that kills them early? I keep hearing/reading 100k miles but not everyone is having them fail?

Yeah I'd heard something about LPG can effect them early. Mine hasn't got an LPG system though so assumed it was the mileage!

markyzs180 · Mar 6, 2017

R222RWD said:
Yeah I'd heard something about LPG can effect them early. Mine hasn't got an LPG system though so assumed it was the mileage!

How do you afford to run it then!!! LOL

markyzs180 · Mar 6, 2017

Just checked the MAF and its sitting at 21-23Kg at 850rpm idle at full temp. Seems in spec...

R222RWD · Mar 6, 2017

markyzs180 said:
How do you afford to run it then!!! LOL

Haha everyone asks me that!! It's not my everyday car, so makes it easier. Stopped raining there yet?! Lol

R222RWD · Mar 9, 2017

Guess who's engine light came on today when driving the disco! When I get chance on the weekend I'm going to plug it in and see what the faults are. I think I spoke too soon earlier this week!!!!!

markyzs180 · Mar 9, 2017

R222RWD said:
Guess who's engine light came on today when driving the disco! When I get chance on the weekend I'm going to plug it in and see what the faults are. I think I spoke too soon earlier this week!!!!!

oh b****x .... if i get home ealy enough tomorrow i'll be swapping out my new bosch sensor and fingers crossed all sorted!
keep us posted pal...

R222RWD · Mar 9, 2017

markyzs180 said:
oh b****x .... if i get home ealy enough tomorrow i'll be swapping out my new bosch sensor and fingers crossed all sorted!
keep us posted pal...

Went out tonight and quickly plugged it in to check and was presented with this! Can they become faulty from lack of use? I know it's a long shot but I've hardly used the car these past few weeks and just wondered considering it was newly fitted in November! Damn oxygen sensors haha

markyzs180 · Mar 9, 2017

R222RWD said:
Went out tonight and quickly plugged it in to check and was presented with this! Can they become faulty from lack of use? I know it's a long shot but I've hardly used the car these past few weeks and just wondered considering it was newly fitted in November! Damn oxygen sensors haha

You've got four codes ther kidda... press the right arrow key to scroll through them.... the only time I've had that error is when I drove it with the sensor unplugged last weekend....

V8 O2 Lambda sensor - changed but EML back on?

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