2013 GMC SIERRA 3500HD

Typical onset: 80,000-150,000 mi

Symptoms: Sudden loss of power, rough running, won't start, Metal shavings in fuel filter, Multiple fuel system codes (rail pressure, injector circuits), Catastrophic failure sends metal through entire fuel system

Fix: Replace CP4.2 pump, all eight injectors, both fuel rails, fuel lines, tank cleaning or replacement, flush system. 20-30 labor hours depending on contamination severity. Many shops recommend CP3 conversion kit during repair to prevent recurrence.

Estimated cost: $8,000-15,000

Typical onset: 150,000-250,000 mi

Symptoms: Excessive blow-by from crankcase, White or blue smoke on startup, Knocking noise from lower end, especially under load, Loss of compression in one or more cylinders, Coolant consumption without external leaks

Fix: Complete engine rebuild or replacement. LML pistons crack at the bowl rim under heat and stress. Requires full teardown, new pistons, rods, bearings, often head gaskets, ARP studs. 40-50 hours for in-chassis rebuild, less if pulling engine. Upgraded pistons recommended.

Estimated cost: $12,000-20,000

Typical onset: 70,000-120,000 mi

Symptoms: DEF quality poor message, Speed limited to 55 mph countdown warning, P20EE, P20E8, P204F codes, DEF heater grid codes in cold climates, Crystallization around injector

Fix: Replace DEF injector and/or quality sensor. Injector requires dropping DEF tank on this chassis. 3-5 hours labor. Use only OEM parts—aftermarket sensors fail quickly. Tank heater grid replacement adds significant labor.

Estimated cost: $800-2,200

Typical onset: 90,000-140,000 mi

Symptoms: Transmission fluid seeping at radiator connections, Pink fluid puddles under front of truck, Low transmission fluid level, Transmission running hot, Coolant contamination in trans fluid (milky appearance) if internal cooler fails

Fix: Replace hard lines and fittings at radiator-mounted cooler, sometimes full cooler. External leaks: 2-3 hours. Internal cooler failure requires radiator replacement, trans flush, possible torque converter replacement if cross-contamination occurred. 6-8 hours total.

Estimated cost: $400-1,800

Typical onset: 100,000-150,000 mi

Symptoms: P0401 insufficient EGR flow, White smoke at startup, Coolant loss with no visible leaks, Rough idle when cold, Power loss, limp mode

Fix: Replace EGR cooler, often with upgraded version. Coolers clog with soot or crack internally, leaking coolant into exhaust. 6-8 hours labor. EGR valve often replaced simultaneously. Some owners delete system where legal, but EPA fines are severe.

Estimated cost: $1,200-2,500

Typical onset: 60,000-100,000 mi

Symptoms: Clunk when shifting from park to drive or reverse, Vibration at idle in gear, Visible sagging of transmission tailshaft, Driveline vibration under acceleration

Fix: Replace rear transmission mount and crossmember bushings. Common wear item on heavy-duty trucks. 1.5-2 hours labor. Inspect driveshaft U-joints and carrier bearing simultaneously.

Estimated cost: $250-500

Typical onset: 50,000-120,000 mi

Symptoms: Hard starting, especially cold, Extended cranking before start, Fuel in water light illuminated, Visible fuel weeping from filter housing, Air bubbles in clear fuel lines

Fix: Replace fuel filter housing assembly with updated revision. OE housing cracks at fittings or water-in-fuel sensor. 2-3 hours including bleeding system. Always replace both filters during service. Aftermarket housings available with better sealing.

Estimated cost: $400-800