Engine Service Light Trouble Codes
How to Check for Trouble Codes
If you see a "check engine" or a "service engine soon" light in your instrument cluster, your car has stored a diagnostic trouble code. This means the computer system on your vehicles has detected a problem within various systems it controls and monitors. Your vehicles has many different sensors that monitor and control the various systems that keep performance, mileage and emissions at an optimum level. If the trouble code light has been illuminated your vehicle enters into "limp mode" this means it is running on a predetermined program that causes poor mileage and increased emissions. To find out what your vehicles computer sees wrong, you will need a simple to use tool called an OBD11 trouble coder reader.
All 1996 and newer vehicles utilize a "D" style plug-in connector that connects to the code reader. On most vehicles the connector is located in the driver's compartment, usually under the dash on the drivers side. Once the code reader is plugged in you can retrieve trouble codes thee ngine computer has stored in its memory. If your car is older than 1996, an OBD1 scanner is required to read the codes. These OBD1 scanners will vary depending on manufacturer. These diagnostic trouble codes are the same codes the dealer and repair shops use to diagnose and repair your vehicle. A code reader can also be used to clear the trouble codes from the computers memory after repairs have been made. An engine trouble code reader is an easy to use tool and is a worthwhile investment for future repairs.
Trouble Code Retrieval Guide
Malfunction Indicator Lamp
The MIL has illuminated during driving this means there is a malfunction trouble code stored in the vehicle's computer.
Locate Your Vehicle's Computer Connector
Locate your vehicle's computer connector (ALDL), most are on the lower driver's side. In some vehicles you might need to look around a little, on the passenger's side, and around the center console under a plastic cover. For more information, check your owner's manual.
Connect your code reader to the under dash connector. The code reader will automatically turn on and prompt you to the next step for code retrieval. Once the code has been identified look up the definition on the trouble code chart supplied with your code reader. After repairs have been made, clear trouble codes and recheck system. After codes have been cleared the computer system is ready for internal testing, this means that while the vehicles is in operation the onboard computer is performing tests on the control and monitoring systems. These tests are called "monitors" most cars have between 4 and 8 monitor systems. Thecomputer goes through its testing procedure in about 40 to 60 miles.
- OBD2 (OBDII) Scan Test is Incomplete - The computer system or PCM (powertrain control module) that controls your car is equipped with a basic operating program. This operating program is designed to control your engine, transmission, emissions, safety systems and more. If a scan has been performed by using a code scanner and a "scan could not be completed" code is retrieved further troubleshooting is necessary. Usually a trouble code P1000 or manufacturers equivalent. We have listed reasons for this condition.
- Stuck Engine Thermostat - If the engine thermostat has stuck open it forces the engine coolant to stay at too low of a temperature causing the computer to stay in open loop. This open loop creates a state of pre-programmed parameters were no diagnostic tests can be preformed. (The PCM is constantly waiting for the engine to heat up to operating temperature)
- Shorted Oxygen Sensor- Coolant Temperature Sensor - The PCM relies on information from main sensors to operate properly; if one of these sensors is severely shorted it can cause the PCM to stay in open loop causing an incomplete systems check.
- Shorted Fuel Injector -If a fuel injector short circuits it can cause the engine not to run by shorting the injector driver in the computer. This in turn can cause incomplete code gathering that can result in a P1000 code.
After a car repair has been performed the MIL (malfunction inductor lamp) indicator will illuminate because the technician neglected to plug in a sensor. A blown fuse can cause the MIL to illuminate. A shorted sensor can also cause the MIL to illuminate.