2007 GMC YUKON

Typical onset: 80,000-150,000 mi

Symptoms: Lifter tick/knocking on cold start that persists or worsens, Check engine light with P0300-series misfire codes or P0521 oil pressure code, Excessive oil consumption (1 quart per 1,000 miles or worse), Metal shavings in oil, loss of power

Fix: AFM lifters collapse due to oil starvation, damaging cam lobes and rockers. Proper fix is AFM delete kit with new cam, lifters, valley cover, tuning. Half-measures (just lifters) fail again. 18-25 labor hours for full delete and reassembly.

Estimated cost: $3,500-6,000

Typical onset: 100,000-180,000 mi

Symptoms: White smoke on startup or under load, Severe oil consumption (1+ quarts per 500 miles), Loss of compression in one or more cylinders, Coolant in oil or oil in coolant (if rings crack piston allowing coolant past)

Fix: Weak piston ring lands on these castings crack under detonation or AFM cycling. Once compression is lost, needs full teardown: pistons, rings, hone or bore, possibly crank polish. Many shops recommend reman short block instead. 30-40 labor hours for in-chassis rebuild.

Estimated cost: $4,500-8,000

Typical onset: 60,000-120,000 mi

Symptoms: Transmission fluid leaking from rubber cooler lines at crimped fittings near radiator, Pink fluid puddles under front of truck, Low fluid level causes delayed shifts or slipping, If line ruptures while driving: instant loss of all fluid, transmission destruction

Fix: Factory crimped rubber lines separate at quick-connect fittings. Replace with solid aftermarket hard lines or OEM updated lines. If caught early, just lines. If driven low on fluid, internal clutch damage means rebuild. 2-3 hours for lines only, 12-18 hours if rebuild needed.

Estimated cost: $300-600 (lines only), $2,500-4,000 (rebuild)

Typical onset: 100,000-180,000 mi

Symptoms: Slipping or flare on 3-4 upshift, No 5th or 6th gear, falls back to 4th, Harsh 2-3 shift or banging into reverse, Metal shavings in pan, burnt fluid smell

Fix: Sunshell cracks or 3-5-R clutch pack burns if fluid not changed every 50k. Once slipping starts, debris contaminates entire unit. Rebuild with upgraded sunshell and Alto or Raybestos clutches. 10-14 hours R&R and rebuild.

Estimated cost: $2,800-4,200

Typical onset: 70,000-140,000 mi

Symptoms: Stabilitrak/traction control warning lights on dash, ABS light illuminated, Speed sensor codes C0035-C0040 (individual wheel sensors), Speedometer drops to zero intermittently

Fix: Front wheel speed sensors corrode at connector or internally due to road salt exposure. Rear sensors less common. Diagnose with scanner to identify which corner. 1-1.5 hours per sensor including cleanup of tone ring.

Estimated cost: $200-350 per sensor

Typical onset: 90,000-160,000 mi

Symptoms: Speedometer, tach, fuel, or temp gauge drops to zero or bounces, Gauges sweep full range on startup then fail, Intermittent operation, worse in cold or hot weather, No check engine light (this is cluster-internal)

Fix: Stepper motors behind gauge needles wear out. Can rebuild cluster yourself with $60 stepper motor kit and soldering iron (3-4 hours DIY), or send to specialist for rebuild (1-2 day turnaround), or replace cluster and reprogram to VIN (2 hours with Tech2 scan tool).

Estimated cost: $150-300 (rebuild), $400-700 (replace and program)

Typical onset: 100,000-150,000 mi

Symptoms: A/C blows warm, system won't hold charge, Oily residue on passenger floor or musty smell, Refrigerant leaks out within days of recharge, UV dye test shows leak behind dash

Fix: Evaporator corrodes from inside due to moisture and refrigerant acid. Buried deep behind entire dash assembly. Full dash removal, HVAC box disassembly, evap replacement, reassembly, vacuum and recharge. 10-14 labor hours.

Estimated cost: $1,200-1,800