1994 Toyota Previa Problem Reports

Most Reported 1994 Toyota Previa Problem Reports

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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.

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.

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.

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.

Over the time the exhaust gas recirculation (EGR) system may become plugged with debris, the oxygen sensor may also be getting slow or 'lazy' around this time. When servicing or cleaning  the EGR system, it is a good idea to replace the oxygen sensor because it works in tandem with the EGR system.

It is important to regularly check the valve clearance as the exhaust valves may become too tight. This will lead to valve failures, which are expensive to repair.

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.

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

At higher mileages (125,000+) the mass air flow sensor may cause the vehicle to idle rough, run rich and even stall. It is recommended to replace the mass air flow sensor with a factory unit because the aftermarket units have very mixed results.

The ignition coil inside the distributor can fail. There will be a hesitation on acceleration, especially when the vehicle is warming up on cold, rainy days. The pickup coil inside the distributor can also fail and cause a no-start condition. There have also been some failures of the radio noise suppressor inside the distributor, which can short out. Our technicians recommend replacing the whole distributor with a complete, genuine Toyota distributor if any of its components fail.

The power steering pump and power steering hoses tend to develop leaks and require replacement.

Usually by 150,000 miles the AC system will need some attention, especially in climates where it is used often. Our technicians tell us that it is best to service the AC system every 2-3 years. This keeps the moisture in the system at a minimum which extends the life of the components.

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.

Our technicians report that by 100,000 miles, the ignition key tends to wear out and should be replaced or it may not work as well in the door locks or ignition lock cylinder.

Typically the AC compressor is worn out by about 150,000 miles in warm and/or humid climates. It is recommended to replace the complete compressor including a new clutch and rpm sensor, and to replace the receiver/dryer as well.