I have a bit of a strange issue that im hoping someone may be able to shed some light on.
I usually don't ask for help as i figure out most issues but this one is baffling me.

A friend of mine has asked me to look at his parents 2011 4.4 l322 after another garage couldnt fix it.
It originally went to a garage due to a dpf fault (full).They supposedly had been doing a lot of short journeys that had caused the dpf to require a forced regen. I have been told that it went back over three times in one month and they forged it to regen and eventually washed their hands of it.

When the car came it it had a large coolant leak. a noise from underneath and i had been asked to look at why the car kept having dpf issues. (no light on a tthe time)

The coolant leak was the upper and lower coolant/thermostat housing which i replaced along with a few other coolant items.

There was a code for the temp sensor in the passenger exhaust manifold (RHD vehicle) i also confirmed that i was getting no temp reading on diagnostics from this sensor. This sensor was replaced and the code dint return and i have a temp reading for the sensor now. this was also the cause of the dpf issue they had

I drove the car for 40 minutes to diagnose the noise underneath which turned out to be the front diff. I replaced the front diff and all was fine for two days.

The problem i now have is that intermittently when stating the vehicle i get a restricted performance message. The code i have for this is P0486-17 Exhaust gas recirculation sensor B circuit - General electrical failure. The car was perfect for two days and now this fault has just appeared. The car drives perfectly when the fault is cleared with no issues at all.

The fault only appears when starting the car not when driving. IT also seems to be more common after the car has sat for a few hours

It is not one of the temperature sensors as they all work correctly when checking the diagnostic data,
Using SDD diagnostics the Egr system al tests fine.

Has anyone come across an actual fix for this fault code. I have found a few other posts but no actual fixes.

P0486-17 Exhaust gas recirculation sensor B is the sensor in the actual EGR.

Mentioning this because there is another very common fault for EGR sensor A - this sensor is in the passenger exhaust manifold=, not in the EGR
Notice that you may have already done that one

Quote:

There was a code for the temp sensor in the passenger exhaust manifold (RHD vehicle)

Quote:

Hi, I had a fault with EGR sensor, fault code P0486-17 (27) Exhaust gas recirculation sensor B circuit - General electrical failure - circuit voltage above threshold

Turned out to be a faulty throttle body. A lot quicker to replace than the EGR and sensor.

Thanks for the reply.

Yes the sensor in the exhaust manifold was faulty and was replaced.

The fact that the car drives perfectly and the fault only occurs on startup are you sure its the egr itself?
There is also a test on JLR SDD that runs the engine at idle, 3000 and 3500 rpm which tests the egr and it passed every time.

Yes i have read the code straight after the fault occurs as other wise the engine is in limp mode.

If i clear the fault the car drives perfectly and the restricted performance disappears . The fault will come back on randomly during startup. It may be later in the day or a few days later.

a few thoughts:

-boost leak - the number one by a long way cause of RP on the 4.4TDV8 and many times the codes point elsewhere

-what I've experienced is that a fault code isn't always the pinpoint of the issue eg I had a turbo actuator code but it was a boost leak

-the above chap I quoted had your code and throttle body was it - these get clogged and I've read a good few times they've been replaced

-clean the MAP and MAF sensors for good measure

-unplug the EGR Sensor B and see what happens

. Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway

Last edited by GGDR on 29th Nov 2020 12:25pm. Edited 1 time in total

I would agree with you on the boost leak if it came on when driving. But it only happens on startup.

The chap i found with the throttle body fault also had another code as well pointing to his throttle body along with a poor idle.

Ive checked both actuators and they both move.

Map sensor has been cleaned which actually made a power difference as it was gummed up

Both maf sensors are working correctly.

Unplugging the temp sensor on the egr give a fault code for it and thats it

I did do a smoke test and had no leaks. I also have a pressure boost leak tester that i will try tomorrow.

I believe it is an electrical fault not a boost leak

boost leak - yep sure but it's worth double checking the hoses just in case.

maybe a slight break in the cable to that sensor if it's that intermittent?

Otherwise I read one guy bought a new sensor (for something else) plugged it in before fitting it to check it would clear the fault. Thought that was smart before hours of disassembly.

So maybe just order the 'B' sensor and try that?
. Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway

Sorry i meant when the temp sensor is unplugged if gives a fault code but not the same one i currently have. I will do a boost leak test tomorrow and go from there. I personally think its an electrical failure somewhere else. Worst case a sticking egr valve maybe

I had an issue a few weeks back, not the same sensor but strange behavior.
Sensor in question is the last one after DPF diagnostics showed it working but not giving a correct reading, and every now and then only at motorway speeds i used to get restricted performance come up but no change to performance.

i did get a replacement sensor but when i went to fit it would not budge and i did not want to remove that section of exhaust. so i inspected the cable that runs from it to the plug and found a few area's where the case had exposed wires and they had corroded. so i cut the damaged cable out and replaced it.

this has sorted the error now and had no issues since.

so it might be worth checking the wires from sensor to plug for issues? 2012 Vogue 4.4 TDV8 - Current
2014 Navara V6 - Gone
2004 Vogue TD6 - Gone
Grand Cherokee - Gone
Discovery V8 (LPG) - Gone
Discovery TD5 - Gone

Thanks for the reply. The fault turned out to be the egr sticking intermittently when first started i could see it happen briefly on live data.

The cold weather made it worse.

They decided to have it mapped rather than have it replaced.

Who’s mapping it out? How will the DPF cope with that? I thought the 2 were reliant on each other.
Tell us more  Gone to a good home: 2011 4.4 TDV8 Vogue SE Buckingham Blue with Ivory and clear glass = "Rory"
2025MY Defender D350 90 in Silicon Silver on coils
1974 Series 3 Lightweight = "Millie"
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The customer decided to get the egr mapped out. It was not mapped by myself but the person/company who did it said that it will not effect the dpf. Im unsure how they can say this but its up to them.

I haven't gone wrong since but time will tell if it blocks the dpf