Your dash has a yellow light that looks like and engine. What do you do now???
If your MIL (Malfunction Indicator Light), commonly called the 'check engine light' or 'cel', comes on randomly it could be caused by low available battery voltage.
Before throwing parts at the problem, start with checking voltage. Use a multi-tester on the DC voltage setting to see if there's enough voltage to have all systems work.
There should be at least 12.6 volts across the terminals with the ignition off. If not, charge the battery for three or four hours at 2 to 5 amps and retest. If the multi-meter shows voltage is still less than 12.6 volts, replace the battery before doing anything else.
If the battery has good voltage, use an OBD2 scanner to see the stored DTCs (Diagnostic Trouble Codes).
Remember, most OBD scanners are going to just give you GENERIC DTC MEANINGS, so depending on the code(s) you find, you may need to dig further for the MANUFACTURER-SPECIFIC DTCs.
Even with Generic DTCs, they may have different meanings from one manufacturer to another. Save yourself time by always checking to see if your vehicle's manufacturer has a different meaning for any stored DTCs. Use a search engine like Google to look up each DTC by entering the vehicle type then the DTC. For example: Ford P0430.
Okay, so how do you know if the DTC you pulled from the vehicle is a manufacturer-specific code? Good question:
- ALL DTCs have a letter followed by 4 numbers, for example: P0302
- Manufacturer-specific DTCs have a letter followed by a 1, for example, if you had a Toyota or Lexus: P1129 Electric Throttle Control System
Remember, the definition of many DTCs may seem vague, so you may need to further diagnose the issue. All the DTC does is to help narrow down where to look. Let's just say your MIL is on and when you connect with the vehicle through the OBD port, you find DTC P0302 stored. Now what?
The DTC (P0302) indicates there's a misfire in cylinder 2. Here again, search is your friend. Check with Google or another search engine to determine which cylinder is number 2 for your vehicle. If you have a V6 or V8 engine, depending on when it was manufactured, the cylinder designation my be different from what you think. The International Standards Organisation (ISO) cylinder numbering scheme is used by most manufacturers since 2002 or 2003 to indicate the location of each cylinder. Bank 1 refers to the RH side of the engine when viewed from the driver's position, while Bank 2 is the LH side.
- Bank 1 (RH side of engine) cylinders 1, 3, 5, 7 for a V8
- Bank 2 (LH side of engine) cylinders 2, 4, 6 ,8 for a V8
So assuming you have a newer vehicle with a V6 engine and coil packs over each spark plug, go to Bank 2, the left front cylinder and remove the coil pack. See if there's oil present in the spark plug well, or signs of cracking or carbon-tracking around the insulator. If there's oil present, clean the coil pack insulator with electrical cleaner. DO NOT use brake cleaner or other cleaners or the insulator may become damaged.
Depending on the age and number of miles/kilometres on the vehicle, it may be a good idea to just change the spark plug and coil pack for that cylinder. Also inspect the electrical connections and wiring loom to the coil pack and fuel injector.
