What causes the 4lo light to flash and the engine light to come on simultaneously?
2 Answers
4lo flashing and the engine light coming on simultaneously indicate issues with the four-wheel drive system and engine faults. Here is the relevant information: 1. 4lo flashing: The 4lo light is the four-wheel drive system fault indicator. When this light comes on, it is necessary to have a mechanic use a diagnostic scanner to read the fault codes to identify the cause of the issue and perform targeted repairs. After repairs are completed, the fault codes should be cleared. The 4lo light flashing when the vehicle switches to the four-wheel drive low-speed cruise mode is a relatively common issue. The faults causing the 4lo light to flash are complex and can only be identified by reading system data. 2. There are many reasons why the engine fault light may stay on, with the following being the most common: (1) Oxygen sensor connector damage or looseness, causing the air-fuel mixture to be too lean or too rich. (2) Poor-quality or substandard gasoline, leading to incomplete combustion of the air-fuel mixture during engine operation. (3) Poor engine maintenance, such as issues with spark plugs, ignition coils, fuel pumps, or clogged fuel lines, causing improper combustion of the air-fuel mixture. (4) The engine requires proper air intake for combustion. A dirty or uncleaned air filter can affect the vehicle's air intake, leading to long-term clogging and potentially causing the engine fault light to come on.
That day I took my old Jeep off-roading, and suddenly the 4LO light started flashing continuously, and the engine malfunction light also turned yellow. I immediately pulled over. Experience tells me that this is most likely an issue with the transfer case, such as a failed oil pressure sensor or gear jamming, causing the system to fail to engage the low-range four-wheel-drive mode properly. At the same time, the engine light coming on indicates that the ECU has detected a related error, such as a transmission sensor failure or a circuit short. Do not continue driving, as this could burn out more components. It's best to take it to a professional shop to read the fault codes with a diagnostic tool for inspection. Regularly changing the transfer case oil and maintaining the sensors can help avoid breakdowns in the wild.
