While Disco was on the lift during head gasket job I replaced all four 02 sensors....I am still getting CEL codes for the 02 sensors after clearing the codes...

why?

 

Number of reasons

wiring could be broken or bad connections. Look closely at wires going into O2 plug.

Vaccum leaks ( smoke test )

exhaust leaks smoke test

bad purge valve. Causes misfires and bad combustion all sorts of headaches. Hyundai part cheap

 

you have a link to the purge valve? Describe this “smoke test”? I’m almost positive there are no exhaust leaks...but vacuum leak....that might be another story.

 

Check out this smoke test I rigged up.

https://landroverforums.com/forum/di...15/#post709433

here is a link to the Hyundai part

Genuine Hyundai 28910-22040 Purge Control Valve

 

I’ve had on going o2 issues on bank 2, there are mini cats installed, I guess to get around cat problems but still faults
they noticed that the o2 lead was close to ht lead, that fixed it for 3 days, now they have swapped over the front sensor lead for the rear, hopefully that will fix it

 

Get an ELM327 off Amazon for $5, free Torque app on an android ($30 android off ebay if you have iphone). CHart the oxygen sensor voltage, post videos here.