Toyota Avalon Problems

RepairPal has identified the most common problems with the Toyota Avalon as reported by actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.

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35
Known Problems

On higher mileage vehicles, an engine misfire may develop and/or the Check Engine Light may illuminate due to a failed ignition coil. It is not uncommon to replace all the coils when the first one fails in order to prevent return trips to the repair shop.

The motor for the rear window sunshade in the Toyota Avalon is known to fail. When this occurs, the sunshade will not extend down the window, and a grinding noise is heard until the motor fails as well. 

Replacement of the sunshade assembly is necessary to correct this failure, however, removing the fuse for the sunshade will stop the motor from making the irritating grinding noise. 

At higher mileages, (125,000-150,000) the automatic transmission may not shift correctly. This can be caused by the throttle position sensor being out of adjustment or a shift solenoid needing to be replaced. Typically the transmission does not need to be completely overhauled.

Debris can get into the idle air control valve. This will restrict the air flow into the engine, causing idle speed and/or stalling when cold. The valve can be cleaned or replaced to correct this concern.

Sludge can build up in the engine because Toyota did not recommend frequent enough oil changes. Lexus will sometimes offer a discount on cleaning the engine if necessary. Owners who changed their oil every 3,000 miles did not experience these problems. This sludge build up can lead to excessive oil consumption.

The VVT-i oil line is known to burst. This is a very large leak which covers the ground, engine, and undercarriage.

If the oil line ruptures while driving, the low engine oil message and engine oil pressure warnings will illuminate. Continued use after these warnings will result in complete engine failure due to oil starvation.

The line is known to be defective, and a revised part has been issued by Toyota, however, this revised part is known for the same issue.

To repair the issue, the line must be replaced, and the engine bay and undercarriage must be cleaned thoroughly.

Intermittent failure of a purge control valve in the evaporative emission system can cause the Check Engine Light to illuminate. A failed valve should be replaced to correct this problem.

 

The Toyota Avalon with the 3.0L V6 engine has a known issue with the valves that if left unchecked, will cause burned valves and engine performance issues. 

The engine ‘breathes’ through valves that are pushed open by the camshaft, and closed by springs. When valves are closed, they seal against a valve seat. In this vehicle, the valve seat is too soft, so after the valve contacts it thousands of times, it becomes crushed. Once it is crushed, the valve can no longer make a proper seal, and the valves erode due to extreme temperature (burnt valve).

Symptoms related to this issue:

To repair the burnt valves, the cylinder head must be removed and rebuilt, which is a costly internal engine repair, however, this issue can be prevented through inspection and adjustment of valve clearances every 40,000 miles.

The Check Engine Light may illuminate because a component of the oxygen sensor stops working. As a result the engine computer is unable to determine the proper ratio of air to fuel for the engine. Replacing the failed oxygen sensor should correct this concern.

 

The 6 cylinder engines have a tendency to leak oil from the valve cover gaskets, especially the one near the firewall.

At 125,000-150,000 miles, the Brake Master Cylinder may need replacing. When replacing the master cylinder, it is critical to adjust the brake pedal to master cylinder pushrod clearance or the brakes can drag and overheat.

A loss of power on the freeway may due to an internally leaking fuel pulsation dampener. This commonly occurs on higher mileage vehicles.

An engine oil leak may develop from one or both valve cover gaskets, especially the one near the firewall.

The EGR System tends to get restricted or blocked with carbon after 100,000- 125,000 miles which will cause an emissions test failure for NOX. If the EGR system is equipped with an EGR temperature sensor it will trigger a Check Engine Light for improper EGR flow. The repair is to clean out the EGR passages and the EGR Temperature sensor. Our technicians tell this repair is pretty straight forward and takes about 1-1.5 hours. It is also wise to verify the EGR system components i.e. the Transducer, EGR Valve and VSV Solenoid at this time.