Brown's Alignment Auto Repair

CHECK ENGINE LIGHT

CHECK ENGINE LIGHT

Check Engine Light service engine soon MILThe check engine light’s technical name is the Malfunction Indicator Light or Lamp (MIL). Your vehicle’s computer turns it on to alert you when something is not working properly with the engine and or emissions system. One of the main functions of the Check engine light is to monitor the vehicles emissions to stay within the Environmental Protection Agency’s pollution guidelines.
Go to EPA website: Vehicle owner OBDII, on-board diagnostics for information about the EPA & OBDII.

 

MAINTENANCE LIGHT

Engine Maintenance required Light, oil, serviceMany customers confuse the MAINTENANCE LIGHT with the check engine light. The MAINTENANCE LIGHT is preset at the factory to come on every so many thousand miles to remind you to have the maintenance done on your vehicle. It does not mean that there is anything wrong with you car. This is mainly for oil services but is also intended to encourage you to keep up with other maintenance like coolant, brake, timing belt, transmission and differential fluid changes. Also, tire rotations, air filter and cabin filter changes in addition to inspecting all of you car’s other systems. Brown’s Alignment Brake & Auto Repair can provide follow and provide the same maintenance schedules as the dealers. We try to use the schedule as a guide any only recommend doing what is necessary.

CHECK ENGINE LIGHT SYSTEM

There are multiple diagnostic systems in cars to identify their problems. From 1995 back each automobile manufacturer had their own on-board diagnostic (OBDI) systems installed in their cars. Starting in 1996 and moving forward all manufacturers standardized the diagnostic system by using the OBDII system. OBDII stands for On-Board Diagnostics. The OBDII system set guidelines for manufactures to follow. These guidelines identified a standard list of diagnostic trouble codes (DTC) to be used by all manufacturers. When the computer detects a problem it stores a trouble code in memory and illuminates the check engine light.  READ MORE ABOUT OBDII

DIAGNOSTIC TROUBLE CODES:

PO100 – PO199 = Fuel and Air Metering / Oxygen Sensors
– PO100 – PO104 = (MAF) Mass Air Flow Sensor / Meter
– PO105 – PO109 = (MAP) Manifold Absolute Pressure Sensor
– PO111 – PO114 = Intake Air Temperature Sensor
– PO115 – P0119 & PO125 -PO126 = Coolant Temperature Sensor
– PO120 – PO124 = (TPS) Throttle Position Sensor
– PO128 = Thermostat
– PO130 – PO167 = Oxygen Sensor / Air Fuel Ratio Sensor (PO135, PO141, PO155, PO161)
– PO171 – PO174 = Lean Condition
– PO172 – PO175 = Rich Condition
PO200 – PO299 = Fuel and Air Metering / Injector Circuit
– PO200 – PO212, PO261 = Fuel Injector
– PO230 – PO233 = Fuel Pump
PO300 – PO399 = Misfire and Ignition System
– PO300 – PO312 = Engine Misfire (PO301, PO302, PO303, PO304, PO305, PO306, PO307, PO308)
– PO325 – PO334 = Knock Sensor
– PO335 – PO339 = Crankshaft Position Sensor
– PO340 – PO344 = Camshaft Position Sensor
– PO350 – PO362 = Ignition Coil
PO400 – PO400 Emissions Control Systems
– PO400 – PO408 = (EGR) Exhaust Gas Recirculation Valve (PO401)
– PO420 – PO434 = Catalytic Converter (PO430)
– PO440 – PO452 = Evaporative Emissions ( PO455)
– PO460 – PO464 = Fuel Level Sensor
– PO480 – PO485 = Cooling Fan
PO505 – PO507 = Idle Control System
P0600-P0699 – Computer Output Circuit
P0700-P0899 – Transmission
P2xxx Generic Power train Diagnostic Codes DTC

There are also B codes which are body codes and C codes which are chassis codes.

Checking the Codes:

When the check engine light comes on the computer has stores codes in its memory. All codes help point the technician in the right direction of the cause. The codes by themselves should not be depended on to solely diagnose the problem. Our technician first checks the vehicle’s computer for code information with a scan tool. For many systems once the codes are checked he/ she can use the scan tool to verify that there is a problem by testing the components. If the scan tool can not verify a problem exists then the tech can also run additional tests to find the cause. A good example of why diagnostics should be run is the PO171 / Po174 codes can be misdiagnosed as an oxygen sensor problem but can turn out to be a vacuum or an evaporative system leak. PO440 codes often require a smoke test (a machine that injects smoke through the lines) to find the source of the leak. A PO401 code indicates an EGR flow problem but many times the EGR valve does not need to be replaced. It is more a matter of cleaning carbon from the valve or cleaning the ports / passage ways leading to the EGR valve. EGR means Exhaust Gas recirculation.

Data Link Connector

The OBDII system also required all auto makers to provide a universal plug for diagnostic computers or scan tool to be connectedrALEIGH AUTO REPAIR DATA LINK CONNECTOR LOCATIONS CHECK ENGINE LIGHT to. This plug called the Data Link Connector and is usually found under the driver side dash. Although there are some cars where the manufacturer felt the need to be creative and hide the connector elsewhere. Some Honda Accords and Acuras have the connector located behind the ashtray. Some Volvos are located in the center console. While some other vehicles have their connector under the passenger dash. When the check engine light is on the technician connects his scan tool to the data connector to retrieve codes and test systems.

Resetting the Check Engine Light

Once the repairs have been completed the codes will be cleared from the vehicles computer with the scan tool. Once this is done the cars computer still has to “reset” itself or become ready to accept new information. This is done by a drive sequence / cycle which is specific for different cars. A drive sequence is a a certain amount of idling, starts, stops and driving at varying speeds for varying amounts of time and also using the heat and or air conditioning. Completing the drive sequence will force the vehicle to activate / run it’s on board diagnostics and reset it’s readiness monitors. This has to be accomplished in order for the vehicle to be “ready” to have a state inspection performed. All manufacturers recommend performing the drive cycle as the appropriate manner to reset the computer. Trying to complete the cycle while driving in traffic can be a challenge and is not always practical. Most vehicles will reset themselves with normal around town driving in about 50 to 100 miles.

Why Does The Dashboard check engine Light Blink Or Flash?

Under certain conditions, the dashboard check engine light will blink or flash. This indicates a rather severe level of engine misfire. When this occurs, the driver should reduce speed and seek service as soon as possible. Severe engine misfire over only a short period of time can seriously damage emission control system components, especially the catalytic converter, which is typically the most expensive to replace. Drivers should also consult their vehicle owner’s manual for manufacturer specific information.