U3979 Toyota Auto Trouble Code

U3979 Toyota OBD2 specifically refers to the camshaft (cam) timing. In this case, if the cam timing is over-retarded, the engine light will be illluminated and the code will be set.

The problem is caused by the variable cylinder management system switching on and off during light throttle conditions, at cruising speeds, or when driving on flat roads. The constant switching causes excessive oil consumption and the trouble codes appear when oil pressure drops to the point where it can no longer operate the VCM system.

U3979 Toyota Possible Solution:

Disconnected, dirty or fouled spark plugs are common causes for engines that won't start. Spark plugs typically need to be replaced every season or 25 hours of use. You should also check that the spark plug gap is set properly. If your spark plugs look good, problems with your ignition system can also preventing a spark. These can range from a faulty spark plug lead, shorted kill switch or flywheel key damage.

U3979 Toyota Description For All Models :

U3979 Toyota Trouble Repair :

When you turn on the ignition, the Service Engine Soon or Check Engine U3979 Toyota light should flash briefly, indicating that the OBD system is ready to scan your vehicle for any malfunctions. After this brief flash, the light should stay off while you drive as long as no problems are detected. You'll be glad to know that your vehicle is equipped with an early warning system that could save you time, money, and fuel in addition to helping protect the car!

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