This procedure covers the inspection and replacement of spark plug wires on the 2012-2017 Toyota Camry with 2.5L I4 engine, including removal of ignition coils and installation of new spark plugs if needed.

Warnings

Tools required

Parts

• Spark plug wires (set of 4) × 1 — Use OEM specification
• Spark plugs (if replacing) × 4 — 90919-01253 or equivalent iridium

Preparation

1. Ensure engine is cool to the touch
2. Park vehicle on level ground and engage parking brake
3. Disconnect negative battery terminal if working near electrical connectors
4. Gather all tools and parts before beginning

Procedure

1. 1

   Remove engine cover
   Grasp the engine cover firmly and pull upward to release the retaining clips. The cover is held by push-clips only and does not require tools to remove. Set aside in a clean area.
2. 2

   Locate ignition coils
   Identify the four ignition coils on top of the valve cover. Each coil sits directly over a spark plug. Note the cylinder numbering from front to rear: 1-2-3-4, with cylinder 1 being closest to the timing belt end of the engine.
3. 3

   Disconnect ignition coil connectors
   Press the tab on each ignition coil electrical connector and pull straight up to disconnect. Mark or note the position if connectors are not keyed differently. Do not pull on the wires themselves.
4. 4

   Remove ignition coil mounting bolts
   Using a 10mm socket, remove the single bolt securing each ignition coil. Keep bolts organized as they will be reused. Note that different model years may have slightly different bolt torque specifications.
   Torque spec

   Ignition Coil Bolt11 Nm (8 lb-ft)
5. 5

   Extract ignition coils
   Grasp each ignition coil firmly and pull straight up with a slight twisting motion to break the seal. The coil boot may stick to the spark plug. If resistance is felt, gently twist while pulling. Inspect the rubber boot inside each coil for cracks, tears, or carbon tracking.
   ⚠Do not pry against the coil body as this can crack the housing
6. 6

   Clean spark plug wells
   Use compressed air or a clean lint-free cloth to remove any debris from around the spark plugs and inside the plug wells. This prevents contamination from falling into the cylinders when plugs are removed.
   ⚠Do not allow dirt or debris to fall into the cylinder when spark plug is removed
7. 7

   Remove spark plugs
   Using a spark plug socket with extension, carefully loosen each spark plug by turning counterclockwise. Once loose, unthread by hand to prevent cross-threading. Remove all four spark plugs and inspect electrodes for wear, carbon buildup, or abnormal conditions.
8. 8

   Inspect old spark plugs
   Examine electrode wear, insulator color, and gap condition. Normal plugs show light tan or gray deposits. Excessive oil, carbon, or unusual wear patterns may indicate engine issues. Replace plugs if electrodes are worn, gap is excessive, or deposits are heavy.
9. 9

   Prepare new spark plugs
   Verify spark plug gap is set to manufacturer specification (typically 0.043 inches for this engine). Apply a small amount of anti-seize compound to the threads of each new spark plug, keeping anti-seize away from the electrode and insulator.
10. 10

    Install spark plugs
    Thread each spark plug by hand into the cylinder head until finger-tight to ensure proper seating and prevent cross-threading. Once hand-tight, use a torque wrench to tighten to specification. Work in a star pattern if possible to ensure even seating.
    ⚠️Never over-torque spark plugs in aluminum heads - this will strip threads and require costly repair
    Torque spec

    Spark Plug20 Nm (15 lb-ft)
11. 11

    Apply dielectric grease to coil boots
    Apply a small amount of dielectric grease to the inside of each ignition coil boot. This improves conductivity, prevents moisture intrusion, and makes future removal easier. Do not over-apply as excess can attract dirt.
12. 12

    Install ignition coils
    Align each ignition coil over its corresponding spark plug and press down firmly until the coil boot seats completely on the spark plug. The coil should sit flush against the valve cover. Install and hand-tighten the mounting bolt for each coil.
13. 13

    Torque ignition coil bolts
    Using a torque wrench, tighten each ignition coil mounting bolt to the specified torque. Use the lower specification (6 lb-ft) if uncertain of the exact model year variation, as this is the more conservative value.
    Torque spec

    Ignition Coil Bolt11 Nm (8 lb-ft)
14. 14

    Reconnect electrical connectors
    Push each ignition coil electrical connector onto its coil until it clicks into place. Gently tug on each connector to verify it is fully seated and locked.
15. 15

    Reinstall engine cover
    Align the engine cover over the mounting clips and press down firmly until all clips engage with an audible click. Ensure the cover is seated evenly on all sides.
    Torque spec

    Engine Cover Clips3 Nm (2 lb-ft)

Reassembly

1. Reconnect negative battery terminal if disconnected
2. Ensure all electrical connectors are fully seated and locked
3. Verify engine cover is properly clipped in place
4. Double-check that no tools or parts were left in the engine bay

Verification

• Start the engine and listen for smooth idle with no misfires or rough running
• Check for any check engine light or misfire codes using an OBD-II scanner
• Verify there are no visible sparks or arcing around ignition coils during engine operation in darkness
• Rev engine gently to confirm smooth acceleration without hesitation or stumbling

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