| Overheating from old radiator | Plastic tanks crack; cores clog with age | Replace radiator, cap, hoses; bleed properly | $350-900 |
| Heater core leak | Corrosion; old coolant; high system pressure | Replace heater core; flush; new hoses/clamps | $700-1600 |
| Thermostat sticking | Cheap parts or debris in cooling system | OEM thermostat; flush; verify fan operation | $150-350 |
| Electric fan/viscous fan weak | Aging clutch or fan control issues | Replace fan clutch or fan assembly; check relays | $250-700 |
| Oil leaks (valve covers) | Hardened gaskets; PCV restriction raises pressure | Valve cover gaskets + PCV service; clean breathers | $250-700 |
| Front cover oil seep | RTV aging; crank seal wear; poor prior reseal | Reseal front cover; replace crank seal | $900-2200 |
| Rear main seal leak | Seal wear; crankcase pressure; high mileage | Replace rear main; inspect flexplate/TC seal | $900-2000 |
| MAF sensor failure | Heat/oil contamination; brittle harness | OEM MAF; repair connector/pigtail; check intake leaks | $250-650 |
| Ignition coil/boot misfire | Aging coils; oil in plug wells; cracked boots | Replace coils/boots; fix valve cover leaks | $300-1200 |
| Injector failure (age/ethanol) | Old pintle deposits; ethanol swelling seals | Replace/clean injectors; new seals; fuel filter | $600-1800 |
| Fuel pump noisy/weak | Old pump; clogged sock; low tank running | Replace pump + sock; inspect wiring and relay | $300-800 |
| Vacuum/boost leaks | Brittle hoses; cracked couplers; loose clamps | Smoke/pressure test; replace hoses/couplers | $150-600 |
| Turbo wear (VG models) | Oil starvation; coked oil; hot shutdowns | Rebuild/replace turbos; add proper oiling habits | $1200-3500 |
| Exhaust manifold cracks/tick | Heat cycling; thin castings; loose hardware | Replace manifolds/gaskets; check studs | $600-1800 |
| Detonation on boost (VG) | Low octane, lean from leaks, weak fuel system | Fix leaks, verify fuel pressure, conservative boost | $200-1500 |
| Timing belt overdue (VG/RB) | Neglect; unknown history on imports | Full timing kit + water pump; inspect idlers | $700-1600 |
| Timing chain guide wear (VQ) | High miles; poor oil changes; guide material wear | Replace chains/guides/tensioners; clean oil pickup | $1800-4200 |
| Sludge from poor oil service | Long intervals; cheap oil; short trips | Drop pan, clean pickup; frequent oil changes | $400-1500 |
| Automatic trans flare/shift issues | Worn clutches; valve body wear; overheated ATF | Service w/ filter; rebuild valve body or full rebuild | $350-3500 |
| Delayed D/R engagement | Internal seal wear; low line pressure; old ATF | Line pressure test; rebuild if persistent | $1200-3500 |
| Torque converter shudder | Lockup clutch wear; contaminated ATF | Correct ATF service; converter replace if needed | $400-1800 |
| Diff whine/leaks | Worn bearings; low fluid; pinion seal aging | Reseal; rebuild diff if noisy; correct fluid | $250-1800 |
| Driveshaft center bearing | Rubber carrier cracks; age and heat | Replace center bearing/support; inspect U-joints | $350-900 |
| Tension rod bushing failure | Fluid-filled bushings split; braking loads | Replace tension rods/bushings; alignment | $300-900 |
| Rear subframe bushing wear | Age; heavy chassis loads; oil contamination | Replace subframe bushings; inspect mounts | $800-2200 |
| Ball joint/tie rod wear | Age; torn boots; poor roads | Replace joints/rods; alignment | $350-1200 |
| Steering rack leaks | Seal wear; contaminated fluid; torn boots | Rebuild/replace rack; flush PS system | $700-1800 |
| Power steering pump whine | Aeration from hoses; clogged reservoir screen | Replace suction hose/O-rings; clean reservoir | $150-600 |
| ABS wheel speed sensor faults | Sensor aging; cracked tone rings; wiring breaks | Scan, replace sensor/repair wiring; clean hubs | $200-800 |
| Window regulator failure | Plastic guides break; motor strain | Replace regulator; lube tracks; check switches | $200-600 |
| Door lock actuator failure | Weak motors; dried grease; age | Replace actuator; service latch mechanism | $150-450 |
| Climate control blend door | Actuator gear wear; control amp failure | Replace actuator/amp; recalibrate if applicable | $250-900 |
| AC compressor failure | Age; low oil; debris from prior failure | Replace compressor+drier; flush; correct charge | $900-1800 |
| Heater/AC blower resistor | Thermal stress; old blower drawing high amps | Replace resistor; check blower motor current draw | $150-450 |
| Cluster/illumination issues | Aging solder joints; dim bulbs; voltage dips | Reflow solder/replace bulbs; check grounds | $150-600 |
| Sunroof drain leaks | Clogged drains; cracked drain tubes | Clear drains; replace tubes; dry/repair rust early | $100-500 |
| Trunk water intrusion | Tail lamp seals; seam sealer cracks; vent leaks | Reseal lamps/seams; replace trunk weatherstrip | $150-700 |
| Ground/connector corrosion | Age, moisture; prior alarm/AV installs | Clean grounds; repair connectors; remove bad splices | $100-800 |
| Immobilizer/NATS issues | Key chip mismatch; hacked wiring; weak battery | Program keys; repair wiring; stabilize voltage | $200-900 |
| Seized alignment eccentrics | Rust bonds bolts to bush sleeves | Cut/replace bolts and bushings; anti-seize | $300-1200 |
| Underbody rust structural | Coastal/snow exposure; poor undercoating | Avoid purchase; repairs exceed value quickly | $1500-8000 |