2012 TOYOTA 4RUNNER

Typical onset: 80,000-150,000 mi

Symptoms: Check engine light with P0418/P0419 secondary air codes, Sudden catastrophic knocking and loss of power after air pump disintegrates, Metal shavings throughout intake manifold and cylinders, Complete engine seizure in worst cases

Fix: When the secondary air pump impeller disintegrates, metal debris enters intake runners and destroys pistons, rings, and cylinder walls. Many shops see complete engine rebuilds or replacements. Short block or long block replacement requires 18-25 hours labor depending on access and damage extent. Preventive replacement of air pump assembly at first sign of noise runs 3-4 hours.

Estimated cost: $6,500-12,000

Typical onset: 60,000-120,000 mi

Symptoms: Ticking noise from engine bay on cold starts that may diminish when warm, Exhaust smell in cabin, Check engine light with lean codes if leak is severe, Visible cracks or broken studs on manifold inspection

Fix: The factory exhaust manifolds crack at the collector or studs snap off in the head. Requires manifold replacement and often drilling/extracting broken studs. Figure 6-8 hours per side for manifold, gaskets, and stud extraction. Both sides often need addressing eventually.

Estimated cost: $1,200-2,400

Typical onset: 90,000-140,000 mi

Symptoms: Transmission fluid dripping from front of vehicle, Low transmission fluid level on dipstick, Burnt transmission smell if fluid level drops significantly, Pink or red fluid pooling under radiator area

Fix: The hard transmission cooler lines corrode where they run along the frame, especially in salt states. Line replacement requires removing skid plates and sometimes exhaust sections for access. 3-4 hours labor plus flushing and refilling the transmission.

Estimated cost: $600-1,200

Typical onset: 70,000-110,000 mi

Symptoms: Clunking from front suspension over bumps, Loose or wandering steering feel, Excessive play when prying on tire at 6 and 12 o'clock positions, Uneven inner tire wear

Fix: The front lower ball joints wear prematurely, especially with oversized tires or off-road use. Requires pressing out old joints and installing new ones, or replacing entire lower control arm assemblies. 2.5-3.5 hours per side including alignment.

Estimated cost: $800-1,400

Typical onset: 80,000-130,000 mi

Symptoms: Flashing 4WD lights on dash with inability to engage 4WD, Grinding or whirring noise from under vehicle when attempting 4WD engagement, Transfer case stuck in 4WD high or low, Error codes related to transfer case shift actuator

Fix: The electric shift motor on the transfer case fails, leaving you stuck in 2WD or unable to disengage 4WD. Motor replacement requires dropping the front driveshaft and accessing the actuator from underneath. 2-3 hours labor for motor only; more if internal transfer case damage occurred from forcing shifts.

Estimated cost: $500-900

Typical onset: 60,000-100,000 mi

Symptoms: Power running boards fail to deploy or retract, Grinding or clicking noise from running board motors, Boards stuck in extended or retracted position, One side works while other doesn't

Fix: If equipped with power running boards, the motors and plastic linkages fail from corrosion and repeated cycling. Motor replacement is straightforward at 1.5-2 hours per side, but often both sides need attention within short intervals. Many owners disable them entirely or retrofit fixed boards.

Estimated cost: $600-1,000