April 5, 2026: LEMON Manuals is launched! Read the announcement.

Ignition System: Inspection

INSPECT SPARK PLUG

NOTE:

Do not use a wire brush for cleaning.
Do not attempt to adjust the electrode gap of a used spark plug.
Spark plug should be replaced every 200,000 km (120,000 miles).

Check the electrode.
1. Using a megaohmmeter, measure the insulation resistance.
Correct insulation resistance:

10 MΩ or higher

If the resistance is less then the specified value, proceed to step (d).

HINT:

If a megaohmmeter is not available, do the following simple inspection instead.

Fig 1: Measuring Insulation Resistance Using Megaohmmeter
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Alternative inspection method:
1. Quickly accelerate the engine to 4,000 rpm 5 times.
2. Remove the spark plug.
3. Visually check the spark plug.
4. If the electrode is dry...OK.
5. If the electrode is wet...Proceed to step (c).
6. Reinstall the spark plug.
Fig 2: Identifying Spark Plug Electrode
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Check the spark plug for any damage to its thread and insulator.

If there is damage, replace the spark plug.

Recommended spark plug:

RECOMMENDED SPARK PLUG TABLE

DENSO made	SK20R11
NGK made	IFR6A11

Fig 3: Identifying Spark Plug

G04088261

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Check the spark plug electrode gap.
Maximum electrode gap for used spark plug: 1.3 mm (0.051 in.)

If the gap is greater than maximum, replace the spark plug.

Correct electrode gap for new spark plug: 1.0 to 1.1 mm (0.039 to 0.043 in.)

Fig 4: Identifying Spark Plug Electrode Gap
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Clean the spark plugs.
If the electrode has traces of wet carbon, clean the electrode with a spark plug cleaner then dry it.

Air pressure:

Blow: 588 kPa (6 kgf/cm2, 85 psi)

Duration: 20 seconds or less

HINT:

If there are traces of oil, remove them with gasoline before using the spark plug cleaner.

Fig 5: Cleaning Spark Plug
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002