2AZFE engine reliability: strengths, watch-outs, and known issues

The most known problem of these engines is stripping of cylinder head bolt threads. Designers incorrectly chose bolt length, and over time a gap appeared under the cylinder head, leading to mixing of oil and coolant. In 2006, the thread length was increased to 30 mm.

Early engines suffered from relatively moderate oil consumption, but after the 2006 update it increased significantly and became a hallmark of the series. The cause of oil consumption was usually coking of oil scraper rings.

The timing drive uses a thin chain that often stretches by 150,000 km. The intake camshaft phaser lasts slightly longer, and they are often replaced together.

These engines do not like prolonged low-speed driving, e.g., in traffic jams. Purely urban engines often experience cylinder bore ovalization by 200,000 km.

Plastic balance shaft gears, water pump, alternator overrunning pulley, and engine mounts have relatively low life. The plastic intake manifold of early years was noisy at low RPM. This engine also tends to coke up, especially the EGR valve in Japanese versions.