Toyota Sienna On the 2007 Toyota Sienna, The P0304 is pointing to a misfire on Cylinder #4. This is the middle cylinder on the side of the engine closest to the front of the vehicle. More commonly, this is due to a faulty Spark Plug, Ignition Coil or Fuel Injector issue. So, best place to start is by inspecting the spark plug. Look for any signs of cracks in the body and/or a worn diode. If there are any doubts, replace all the spark plugs. If the plug checks ok, you can…
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2006 Toyota Sienna P0057 Oxygen Sensor
Toyota Sienna On the 2006 Toyota Sienna, the “Sensor 2’s” (aka “Downstream”) sensors are NOT A/F Sensors. They are “Heated Oxygen Sensors“. Only the “Sensor 1’s” (aka “upstream”) Sensors are A/F (Air/Fuel Ratio) Sensors. So… with the P0057, this is pointing to a fault with the internal heater for the Bank2 Sensor2 Oxygen Sensor. The on-board computer uses this internal heater to get the sensor to normal operating temps within a matter of seconds on cold starts. When it tries to activate the heater and sees no response, the P0057…
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