1997 Toyota Avalon Problem Reports
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At higher mileages, an anti-lock brake system wheel speed sensor may wear out and illuminate the ABS warning light. It is recommended to replace the sensor with a factory part and be sure to clean all rust and debris from the mounting area because the mounting distance is critical. Failure to do so may result in the new sensor setting false trouble codes. Be sure to check the condition and runout of the front wheel bearings on the 2WD and 4WD vehicles and the CV joints on the 4WD vehicles since worn wheel bearings and/or CV joints can cause the ABS trigger rings to rub against the ABS sensors and damage them.
The mass air flow sensor on higher mileage cars occasionally needs to be cleaned or replaced if sluggish acceleration is experienced or the Check Engine Light is illuminated with a mass air flow meter sensor fault code stored.
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.
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 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 Evaporative system may have problems with the vapor canister releasing charcoal pellets that plug the vent valve. Typically a Code P0441, P0442 and P0446 will be set. The key code is the P0446 which is a vent valve electrical failure. The proper repair is to replace the entire canister with all the valves as a unit. This is located on top of the fuel tank and is expensive. Our Technicians tell us that for awhile Toyota was covering these problems, but this may have changed. It would not hurt to call the dealer if this problem occurs to see if Toyota is still helping with these repairs.
A rough idle and even an emissions inspection failure for high HC and CO can be caused by improperly adjusted valves. Also, exhaust valves may become to tight which can lead to valve failures. Our technicians tell us that regular valve adjustment inspections are a must.
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.
If the engine will not crank over, the most common problem is the starter. These will tend to go out at about 100,00-125,000 miles. Sometimes it is only the starter solenoid, but often the complete starter (including solenoid) needs to be replaced.
An engine oil leak may develop from one or both valve cover gaskets, especially the one near the firewall.
The Throttle Position Sensor can get out of adjustment due to wear in the throttle body or due to carbon build up. This will cause the idle timing to advance more than 30 degrees which will cause very high HC and NOx emissions. Conversely, the Throttle Position Sensors can wear out and not properly advance the timing which causes a lack of power and poor fuel economy.
The 6 cylinder engines have a tendency to leak oil from the valve cover gaskets, especially the one near the firewall.
The idle air control motors tend to become carboned up at around 100,000 miles and will cause a start and stall and/or stalling at stop sign problems. Many times these valves can be cleaned, however, the sure bet is to replace the idle air control motor and clean the throttle body.