2002 Highlander

Customer complaint: car was running rough and it was not drivable.
Diagnose: one coil pack was not working.
Solution: replace the bad coil, inspect the other ignition components.
Work done: After testing the ignition system, the coil on cylinder no. 4 was found defective. Although the car didn’t run long with only three cylinders, the spark plugs were fouled with carbon. Also the gap was not according to the specifications. Maintenance time was coming soon, so all the spark plugs were replaced. As you can see in the photos, one DTC was related to an “inefficient catalytic converter”, which might have been caused by the car running too rich. After completing the repair, all DTC codes were erased.