Repair Guide: Ignition Coil Replacement for 2004 Volvo XC90

Ignition coil failure is not an everyday problem associated with the Volvo XC90 2004 model, but sporadic failures can occur, causing misfires, poor fuel economy, and illuminated check engine light.

Tools and Materials Required:

• Ignition coil
• Spark plug
• Ohmmeter
• Basic wrench set
• Screwdriver set
• Extension bar
• Ratchet
• Spark plug gap tool
• Dielectric grease

Diagnostic Steps:

1. Check for a misfire: A failing ignition coil can cause one or more cylinders to misfire. You'll notice this as your Volvo's engine begin to run rough or fail to run smoothly.

2. Use an Ohmmeter: You can test an ignition coil pack by using an ohmmeter, which measures electrical resistance. A good ignition coil should have a resistance reading of between 0.75 and 0.81 ohm.

3. Check Engine Light: If your check engine light is on, use an automotive diagnostic scanner to read the error code. Error codes related to the Ignition Coil will range from P0300 to P0312.

Replacement Steps:

1. Disconnect Battery: Before starting, disconnect the negative battery terminal to avoid shorts or injuries.

2. Remove Engine Cover: Remove the engine cover using a correct-sized screwdriver. This will expose the ignition coil and spark plugs.

3. Identify Bad Coil: Locate the faulty ignition coil. If you’ve run the diagnostic test, you’ll know the code for the misfiring cylinder.

4. Remove Ignition Coil: Unplug the electrical connectors from the ignition coil. Unscrew the bolts using a ratchet and extension bar. Pull out the ignition coil.

5. Replace Ignition Coil: Compare the new ignition coil to the old one to ensure they’re identical. Apply dielectric grease to the inside. Insert it into the cylinder and secure it.

6. Reconnect Everything: Connect the electrical connector to the ignition coil. Reinstall the engine cover and reconnect the battery.

Pitfalls and Tips:

• If the check engine light still comes on after replacement, you may need to clear your car computer's memory using an error code scanner.

• If misfiring persists, consider replacing spark plug of the affected cylinder.

• Remember that the problem could also be a damaged spark plug wire. Inspect each wire thoroughly before replacing an ignition coil.

• Do not touch your ignition coil pack with your bare hands if you've just driven your car, it could be very hot.