Bought a 2014 Silverado new in Aug 2014. I bought extended warranty to 120km or 6 years. On 11/10/18 had 97800km on it took it to dealer because check SES was coming on for PO420/PO430 CAT LOW EFFE and P106 MAP SENSOR PERF. Dealer silicone duct to resonator-cleaned throttle body and said it was good. On 11/24/18 had 98300 km and SES light back on PO430 BANK 2 CAT MELTDOWN. Dealer replaced Cat converter and said it was good .On 03\16\19 SES light back on PO106 MAP SENSOR PERF and PO420/30 CAT LOW EFFE BOTH BANKS. Dealer cleaned MAP Sensor and replaced Air duct assembly from air cleaner to throttle body. On 03\23\19 106280 km SES light back on dealer removed Ypipe and confirmed CAT damaged replaced CAT Converter cleared DTCS and road tested. SES light came back on at 115000 km took it back to the dealer and Codes 420\30 came back on and the CAT was gone again. Dealer had the truck for 10 days and said the reason it keeps burning out CATS is because I put a K&N air filter in and that voids my warranty. The service manager said go ahead and drive it wont hurt anything. On 03\14\20 127500 kms engine blew had it towed to dealer and they say it was 3litres low on oil and plugs were fowled. Talked to the tech and he said oil was not low enough to cause engine failure. They want $12000 to put a new engine in. Im not sure if I should pay or the dealer or if we should split it. Any help would be great

 

oiled aftermarket filters can damage the maf sensor. When the maf sensor is skewed it can run either lean or rich...most likely lean. .u don't mention the engine misfiring. was the check engine light flashing when you were driving it.

were the plugs oil fouled or fuel fowled...fuel would be black...oil would probably leave an ash residue.
the question is....does a skewed maf cause an engine to burn oil? To me it depends on how much fuel was washing into the cylinders. Was the oil burning condition caused by the afm system? were the oil control rings plugged?
if lack of oil didn't kill the engine...what did? I don't believe in aftermarket filters as they can cause dust out...they don't filter enuff and you end up with scorred cylinder walls. That said I don't see every engine with a kand n burning oil. Not enuff info for me to make a conclusion.

the position i would take is...they diagnosed the vehicle on multiple occasions.... to catch this before it blew up. Speak to the dealer principal.

 

Thank you for the info. The engine wasn't misfiring, check engine was on steady and looking at the plugs they look fuel fouled.

 

What did the dealer say specifically what caused the catastrophic engine failure?? 3 liters shy on an 8quart capacity would not cause engine failure. If you are fouling plugs you are blowing it passed the rings or pcv system . Do you have an oil catch can on your engine ??