Due to the age of the vehicle, gaskets and seals may have deteriorated, causing oil leaks.

The timing belt may wear out or break, which can cause significant engine damage if not replaced at recommended intervals.

The cooling system components such as the radiator, water pump, or thermostat may fail, leading to engine overheating.

Clogged or malfunctioning fuel injectors can cause poor engine performance and reduced fuel efficiency.

Worn-out spark plugs or faulty ignition coils can result in misfires and poor engine performance.

Cracked or broken vacuum lines can lead to rough idling and poor acceleration.

Carbon deposits can accumulate on the intake valves and combustion chamber, leading to reduced engine efficiency and performance.

The 1NR-FE engine, particularly in earlier years, is known to consume more oil than expected, which could lead to low oil levels and potential engine damage if not monitored regularly.

Owners have reported that this engine can produce more noise than other engines in its class, which could be due to piston slap or other internal component issues.

The timing chain might wear out prematurely, leading to a rattling noise and potentially causing serious engine damage if it fails completely.

Some users have experienced worse-than-expected fuel economy, which could be due to various factors including engine tuning issues or problems with the fuel injection system.

Problems with the throttle body can lead to erratic idling or poor acceleration, which may require cleaning or replacement of the throttle body unit.

Issues with the cooling system, such as radiator leaks or thermostat failures, can lead to engine overheating if not addressed promptly.

Over time, ignition coils may fail and cause misfires, leading to rough engine operation and potentially damaging the catalytic converter if left unresolved.

The Exhaust Gas Recirculation (EGR) valve can become clogged or fail, leading to poor engine performance and increased emissions.

Various engine sensors, such as the oxygen sensor or mass air flow sensor, may fail, leading to incorrect air-fuel mixture and poor engine performance.

Over time, gaskets and seals can deteriorate and cause oil leaks, which can lead to low oil levels and potential engine damage.

Issues with the cooling system, such as a faulty thermostat, radiator problems, or a water pump failure, can cause the engine to overheat.

Dirty fuel injectors, a clogged air filter, or a malfunctioning oxygen sensor can reduce fuel efficiency.

Can be caused by issues such as vacuum leaks, dirty or faulty spark plugs, or a malfunctioning idle air control valve.

Could be due to problems with the fuel system, exhaust system, or ignition system, leading to reduced engine performance.

If the timing belt is not replaced at recommended intervals, it can break and cause severe engine damage.

Often caused by using low-octane fuel or carbon buildup in the combustion chamber, leading to pre-ignition or detonation.

Can be triggered by a variety of issues, including a faulty sensor, emissions problems, or engine misfires.