Parts for your 2006 Toyota Mark x-Ignition coils

Ignition coils for the 2006 Toyota Mark X (GRX120/121)

Based on technical sources including the Toyota Mark X GRX120/121 Repair Manual, Toyota Electronic Parts Catalogue, and Denso ignition component catalogues for the 4GR‑FSE and 3GR‑FSE engines, the 2006 Toyota Mark X uses individual coil‑on‑plug ignition coils (six in total). That makes ignition coils absolutely relevant to this model.

On the 2006 Mark X, each cylinder gets its own coil perched directly on the spark plug. These coils step the battery’s 12 volts up to the high voltage needed to jump the plug gap, ensuring a strong, precisely timed spark for clean combustion. With the Mark X’s direct‑injection V6, healthy coils are crucial for smooth idle, crisp throttle response, and good fuel economy.

Ignition coils aren’t a scheduled replacement item, but they’re often assessed whenever spark plugs are serviced (typically around 100,000 km on the GR engines with iridium plugs). A scan tool check for misfire trouble codes (P0300–P0306) or coil circuit faults (P0351–P0356) is a smart first step if there’s a stumble or rough idle. Many techs use a simple “swap test”: move a suspected coil to another cylinder and see if the misfire follows.

• Common symptoms of a failing coil: rough idle, hesitation on acceleration, hard starting, increased fuel use, and a flashing or steady check‑engine light.
• Replacement tips: disconnect the battery, lift off the engine covers, unplug the coil, remove the hold‑down bolt (torque on refit is typically about 8–10 N·m), and pull the coil straight up. Inspect the rubber boot, replace boots if they’re cracked or oil‑soaked.
• Good practice: fit quality OEM‑equivalent coils (often Denso for Toyota), renew spark plugs on schedule, and keep oil out of the plug tubes by addressing any rocker cover gasket leaks.
• Diagnosis notes: misfires under load often point to weak coils or widened plug gaps, moisture or coastal conditions can accelerate boot breakdown in AU/NZ climates.

Coils don’t really “wear out” on a timetable, but heat cycles do take their toll. Replacing just the failed unit is fine, though some owners choose to replace coils in pairs or as a full set once multiple units show their age. Keeping the ignition system in top nick will help the Mark X run sweetly for many more kilometres.

How many ignition coils does a 2006 Toyota Mark X have?

It has six coils in total, one coil per cylinder in a coil‑on‑plug arrangement. They sit under the engine covers on top of each spark plug, across both cylinder banks of the V6.

When should ignition coils be replaced on a Mark X?

There’s no fixed interval. Replace a coil when there are misfire symptoms or fault codes pointing to a specific cylinder, or when inspection shows heat damage or cracking. It’s sensible to check coils whenever you replace spark plugs around the 100,000 km mark.

Can a faulty coil be diagnosed at home?

Yes. Scan for P0300–P0306/P0351–P0356 codes, then do a swap test by moving a suspected coil to another cylinder. If the misfire code follows the coil, that coil is likely the culprit. Always rule out worn plugs and oil in the plug tubes before condemning the coil.