2006 Chevrolet Suburban Problems: 10 Known Issues

On the 2003-2007 Chevrolet Suburban, the electronic (drive-by-wire) throttle system triggers a 'Reduced Engine Power' / 'Engine Power Is Reduced' limp mode that sharply limits acceleration and speed - dangerous when it strikes in traffic. The cause is usually the throttle actuator control (TAC): worn internal throttle-body sensors/motor, or a broken/chafed wire in the harness a few inches from the throttle-body connector. Correlation codes P2135 and TAC-performance code P1516 are typical.

On the 2000-2007 Chevrolet Suburban, the Gen III/IV LS-based Vortec V8s use a plastic (nylon) intake manifold with molded silicone/rubber gaskets. With heat cycling and age the gaskets harden and crack, creating an unmetered vacuum leak that leans out the mixture and can weep oil at the manifold-to-head sealing surface. Owners report rough/lean idle, hesitation, and lean-bank misfire codes. Not to be confused with the earlier 5.7 CSFI issue - this is the plastic-manifold sealing failure common across the GMT800 run.

On the 2000-2006 Chevrolet Suburban, on Gen III Vortec V8s the two knock sensors sit in the lifter valley beneath the intake manifold, under a plastic cover. Water and debris collect in the valley and corrode the sensor connectors and wiring; the factory connectors also embrittle from heat. The result is an intermittent knock-sensor signal that sets P0327 (front sensor) and/or P0332 (rear sensor), illuminating the check engine light.

On the 2000-2006 Chevrolet Suburban, early GMT800 Vortec V8s are known for cold-start 'piston slap' - a brief knock/rattle for the first several seconds to a minute after a cold start that fades as the engine warms. GM attributes the noise to an interaction between carbon formed on the piston, the piston motion and the cylinder wall. GM considered it a cosmetic characteristic and issued no recall; it typically does not affect longevity or performance.

On the 1994-2006 Chevrolet Suburban, the 4L60E automatic behind the half-ton Suburban is notorious for burning up the 3-4 clutch pack. The 3-4 apply circuit is long and loses pressure as valve-body bores wear, so the clutches overheat and glaze. Symptoms are slipping in 3rd/4th, a jump from 2nd straight to 4th, or a sudden loss of 3rd and 4th (RPM flares, no forward pull in higher gears while reverse and low gears still work). The input drum can also crack, and the pot-metal sun-gear shell ("sun shell") strips teeth, causing loss of reverse.

On the 2003-2006 Chevrolet Suburban, the 2003-2006 (GMT800) analog cluster uses tiny Switec/Juken X27.168 stepper motors to drive each gauge needle. These motors wear and lose steps, so the speedometer, tachometer, fuel, and temperature gauges stick, read wildly wrong, sweep erratically, or drop to zero while driving. It usually starts with one gauge (often speedometer or fuel) and spreads to the rest. Dim or dark odometer/PRNDL segments from cracked circuit-board solder joints are a related failure. GM issued an extended warranty on affected clusters that has since expired.

On the 2000-2007 Chevrolet Suburban, the exhaust manifold retaining bolts fatigue and snap from repeated heat-cycling on the Vortec V8s. As clamp load is lost the manifold-to-head seal leaks, producing a ticking/chuffing 'exhaust leak' noise that is loudest on cold start and quiets as the metal expands and warms. Owners often smell exhaust near the wheel well. Broken bolts are frequently found rusted/seized in the head, complicating the repair.

On the 2000-2025 Chevrolet Suburban, the transfer case on the 4WD Suburban develops fluid leaks from the front and rear output shaft seals, the input shaft seal, or the case halves where the case splits. The NP246 (half-ton) and NP261/NP263 (heavy-duty) transfer cases all share this tendency. On the NP246 (Autotrac) case, low fluid causes the internal clutch pack to overheat and burn, and on any case low fluid leads to expensive internal damage. The rear output seal is the most common leak source, and the leak often drips onto the exhaust, creating a burning fluid smell. Many owners do not realize the transfer case has its own fluid that needs periodic changing.

On the 1999-2007 Chevrolet Suburban, the plastic gears inside the HVAC blend/mode door actuators strip out, so the door can't move. The classic symptom is a repetitive clicking or tapping from behind the dash (near the glovebox/center) when starting the truck or changing temperature, plus one side blowing hot while the other blows cold, or air stuck on defrost/one temperature. Mode-door actuators fail the same way but click when switching vent/floor.

On the 2000-2006 Chevrolet Suburban, a widely reported clunk/knock felt in the steering wheel and column, most noticeable turning at low speed over bumps or during small back-and-forth steering inputs. The telescoping upper intermediate steering shaft loses its internal lubrication and the splines take up play with a metallic clunk. GM documented it in TSB 00-02-35-003M covering 2000-2006 Suburban/Tahoe.