Why do the Toyota RAV4 malfunction light and 4WD light come on together?
2 Answers
Toyota RAV4 malfunction light and 4WD light come on together for the following reasons: 1. Excessive carbon deposits in the throttle or engine: Too much carbon deposit can affect the normal operation of the engine, causing the malfunction light to come on. Immediate inspection and cleaning of carbon deposits are required. 2. Oxygen sensor failure: This fault can cause an imbalance in the air-fuel mixture ratio, resulting in the engine malfunction light coming on. Timely factory inspection is needed. 3. Long-term low-speed driving: Change driving habits to maintain normal vehicle operation. 4. Fuel injector leakage: Fuel injector leakage can cause an overly rich air-fuel mixture, leading to unstable idle speed after deceleration, and in severe cases, engine stalling. Immediate repair and installation of a new fuel injector are necessary.
When the malfunction indicator light and 4WD light on my Toyota RAV4 both come on, my first reaction is to check the differential oil, as low levels can easily cause issues. Insufficient oil may cause the four-wheel-drive system to overheat, triggering the protection mechanism and illuminating the warning lights. I also inspect the wiring harness connections for looseness, especially around the rear axle, as loose connections can lead to signal loss—sometimes just tapping them can reset the system. If that doesn’t work, I plug in an OBD scanner to read the trouble code, which usually points to the wheel speed sensor or control module. Once, my car had this issue, and the code indicated a dirty sensor—cleaning it cost me around a hundred bucks to fix. When using 4WD in daily driving, avoid being too aggressive, like constantly driving through mud, as it puts extra strain on the system and can trigger false warnings. During regular maintenance, take the time to inspect the 4WD components to prevent problems. If all else fails, take it to an authorized repair shop—don’t delay driving it like that.
