The iridium tipped long life spark plugs in a ninth generation (2003-2008) Toyota Corolla can last up to 120,000 miles in normal operating conditions. But it’s still a good idea to inspect them at about 60-80,000 miles and replace them at around 100,000 miles. For my complete guide to replacing the spark plugs in a 1ZZ-FE 1.8L I4 engine, click on the text link or thumbnail image below.
Toyota Corolla Spark Plug Replacement Guide
