🔧 RX350 - Ignition Coil Replacement

Your RX350 has 6 ignition coils (one per cylinder). Replacing a coil is mostly unplug-and-bolt, but the rear 3 coils (closest to the firewall) take extra work because the upper intake plenum sits over them.

Difficulty Level: Intermediate | Estimated Time: 1.0-3.5 hours

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⚠️ Safety & Precautions

• Work on a fully cool engine; the rear bank area gets very hot.
• Disconnect the negative battery cable before unplugging coils to prevent electrical damage.
• Do not pull on wiring; release connectors by the locking tab first.
• If you remove the upper intake plenum, cover the intake ports with clean rags immediately so nothing can fall in.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 8mm socket
• 3/8" ratchet
• 3/8" torque wrench (5–30 Nm range)
• 3/8" extension set (3", 6")
• Trim clip removal tool
• Flat-blade screwdriver
• Needle-nose pliers
• Telescoping magnetic pickup tool
• Shop rags
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 1 (or Qty: 6 if replacing all)
• Upper intake plenum gasket set - Qty: 1 (if removing plenum for rear coils)
• Throttle body gasket - Qty: 1 (if removing throttle body)
• Dielectric grease - Qty: 1 (optional)

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Open the hood and let the engine cool completely.
• Disconnect the negative battery terminal using a 10mm socket, then tuck the cable aside so it can’t spring back.
• Decide your scope: front 3 coils are easy access; rear 3 coils require upper intake plenum removal.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Lift the plastic engine cover straight up to release it from the rubber grommets (no tools).

Step 2: Replace a front-bank ignition coil (easy access side)

• Locate a coil on the front bank (closest to the radiator).
• Press the connector lock tab and unplug the coil connector by hand. A “lock tab” is the small clip that holds it in.
• Remove the coil hold-down bolt using a 10mm socket and 3/8" ratchet.
• Twist the coil slightly, then pull it straight up to remove it.
• If using dielectric grease, apply a tiny smear inside the new coil boot (the rubber sleeve). Too much can cause misfires.
• Install the new coil straight down until fully seated.
• Reinstall the hold-down bolt using a 10mm socket, then Torque to 9 Nm (80 in-lb) with a 3/8" torque wrench.
• Reconnect the electrical connector until it clicks.
• Repeat for the other front-bank coils if needed.

Step 3: If replacing rear-bank coils, remove the air intake tube

• Loosen the intake hose clamps using an 8mm socket (some clamps may use a flat-blade screwdriver).
• Disconnect any small breather/vacuum hoses using needle-nose pliers to slide clamps back, then twist hoses off gently.
• Remove the intake tube and set it aside.

Step 4: Remove the throttle body (for access)

• Unplug the throttle body electrical connector by hand.
• Remove the throttle body mounting bolts using a 10mm socket and 3/8" ratchet.
• Lift the throttle body off and set it aside carefully.
• Remove and discard the old gasket; install a new gasket during reassembly.
• When reinstalling later, Torque throttle body bolts to 10 Nm (89 in-lb) using a 3/8" torque wrench.

Step 5: Remove the upper intake plenum (rear-bank access)

• Disconnect vacuum/EVAP lines and any wiring brackets attached to the plenum using needle-nose pliers, a trim clip removal tool, and a flat-blade screwdriver as needed.
• Remove the upper plenum fasteners using a 10mm socket, 3/8" ratchet, and extensions.
• Lift the plenum straight up and out.
• Immediately stuff clean shop rags into the exposed intake openings.
• During reassembly, install new plenum gaskets and Torque upper intake plenum fasteners to 21 Nm (15 ft-lb) using a 3/8" torque wrench.

Step 6: Replace the rear-bank ignition coils

• One at a time, unplug each rear coil electrical connector by hand.
• Remove each coil hold-down bolt using a 10mm socket and 3/8" ratchet.
• Pull the coil straight up and out.
• Install the new coil, reinstall the bolt, and Torque to 9 Nm (80 in-lb) using a 3/8" torque wrench.
• Reconnect each coil connector until it clicks.

Step 7: Reassemble everything

• Remove all shop rags from the intake openings (double-check).
• Reinstall the upper intake plenum with new gaskets using a 10mm socket and 3/8" ratchet, then Torque to 21 Nm (15 ft-lb).
• Reinstall the throttle body with a new gasket using a 10mm socket, then Torque to 10 Nm (89 in-lb).
• Reinstall the intake tube and tighten clamps using an 8mm socket.
• Reinstall the engine cover by pressing it back into the grommets.
• Reconnect the negative battery terminal using a 10mm socket and tighten securely.

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✅ After Repair

• Start the engine and let it idle for 2–3 minutes; it should run smooth (no shaking).
• Check for a check-engine light and listen for any hissing (a hissing sound can mean a vacuum leak).
• If you had a misfire code, clear codes with a scan tool and road test.
• After the test drive, recheck that all hose clamps and connectors are fully seated.

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💰 DIY vs Shop Cost

Shop Cost: ₹12,000–₹30,000 (parts + labor, depending on 1 coil vs all 6)

DIY Cost: ₹3,000–₹18,000 (parts only, depending on 1 coil vs all 6)

You Save: ₹9,000–₹12,000+ by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-3.0 hours.

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🎯 Ready to get started?

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