CHK ENGINE LIGHT
For every motorist it is most annoying :sosad: if “CHECH ENGINE” yellow light pops-up while driving along. It is the most misunderstood indicator on your dashboard, the "check engine" light can mean many different things, from a loose gas cap to a seriously malfunctioning engine loosing power.
You do not have to pull the car over to the side of the road and call a tow truck. Still you can drive your car safely. But, you should get the car checked professionally for engine relate fuel system, cooling system, exhaust system, EGR system and EVAP system, as soon as possible. Ignoring this warning, may lead you end up damaging engine or degrading performance by loosing fuel economy and emitting higher levels of pollutants.
Here are some simple steps for Do-It-Yourself….
Just simply do not throw parts one-by-one, make sure it is faulty before you replace. If you do not know how to check particular component, ask :ugh3: , some one will definitely help you out here.
In Toyota Corolla, there are certain sensors inputs to ECU Engine Control Unit which can trigger "Check Engine". These are....
Engine coolant Temperature sensor
Mass Air flow sensor
Crank shaft Position Sensor
Throttle position sensor
Park / neutral gear Selector Position
Vehicle Speed Sensor
Knock Sensor
Power steering Oil Pressure
Intake Air Sensor
Fuel / Vapor Pressure
Absolute Manifold Pressure
Oxygen / Air-fuel Ratio Sensor
EGR –Flow / Temperature Sensor
If you can start and steer your car well and smoothly from extreme right and left, but, still inspect for power steering fluid loss or leakage. If, still Check Engine light remains on you should target last three sensors. Possible causes are:
1. improper fuel pressure.
Leak in fuel system, may be pin-hole, To detect this fill-up your tank to the maximum, park your car in a clean space for a while 5 to 10 min. and check the for the fuel leak on the bottom, if there is any, may be because of loose Gas Cap, Fuel intake pipe, Gas Tank or Fuel lines.
2. Leak in Exhaust system. Can be detected and fixed very easy.
3. Fuel injector restricted. Use Fuel Injector Cleaner several times.
4. Engine coolant Temperature sensor (DCT Code : P0115)
Check Engine Cooling Sytem and radiator circuit for any possible leakage.
Inspect Radiator and hoses connection for leaks. Keep checking level of radiator coolant very often. If there is no leak...
A thermistor built into the engine coolant temp. sensor changes the resistance value according to the engine
coolant temp.
DTC - P0115 Open or short in engine coolant temp. sensor circuit
-Open or short in engine coolant temp. sensor circuit
-Engine coolant temp. sensor
Follow these steps.
(a) Disconnect the engine coolant temperature sensor connector.
(b) Connect the terminals 1 with 2 of the engine coolant temperature
sensor connector. Measure the resistance between terminal 1 and 2. check for open circuit or short circuit. Ideally it should read between 2.0 Kohms to 3.0 Kohms.
(c) Turn the ignition switch ON. Start the vehicle.
(d) Measure the resistance between terminal 1 and 2. As the coolant temperature starts rising up, the resistance starts falling down. At 180 deg C it should read approximately 0.2 Kohms, depends on make.
If the ECM detects the DTC P0115, it operates fail safe function in which the engine coolant temperature is assumed to be 80_C (176_F).
5. EGR – Exhaust Gas Recycle (DTC Code: 71 or P0401)
EGR system reduces NOx output by re-circulating portion of exhaust gases with normal air-to-fuel charge in the engine. EGR Flow is higher while cruising and mid-range acceleration when typical combustion temperature is very high. At lower speed and light load condition lower EGR flow is required. No EGR flow is required while idling or engine warm-up. There are four major components in EGR system, EGR Valve, EGR Vacuum Modulator, VSV: ECU controlled Vacuum Switching Valve and EGR Gas Temperature Sensors plus piping. With the age of the vehicle, EGR system problem is very common.
Use this routine:
-Remove the EGR Vacuum Modulator from the holding clamp and open the top cap. Inspect and replace the filter if required. Diesel (without any rust inhibitor additives or contents) can be used for removal of carbon deposits in the piping.
-Remove the EGR Valve from the mount. Remove the EGR inlet and outlet pipes from the exhaust manifold and the intake manifold. Blow air in inlet port and check for external and internal leaks. Inspect and replace the gasket if required. Inspect the manifold EGR ports and the EGR inlet and outlet pipes for a blockage caused by excessive deposits, casting flashing or other damage. Diesel (without any rust inhibitor additives or contents) can be used for removal of carbon deposits in the piping (A heavy guitar string on a drill motor works real good for running thru the manifold passage to open up the port). Then re-install the EGR and road-test again and also try cruise control at various speeds. If the light doesn't come on, you know that was the problem.
-Check EGR Temperature Sensor.
- Check and clean inlet and out let ports plus electrical connector of EGR VSV. ECU uses three signals to control the operation of EGR VSV switch --- distributor signal, coolant temperature signal and vacuum pressure signal. So after carrying out EGR system maintenance, you should service clean up for distributor cap and clan up electrical contacts of distributor, engine coolant temp sensor and vacuum sensors.
Again, with the age of the vehicle, this is very common.
6. Defective heated Main oxygen sensor No. 1. (DTC code: P0130, P0133, P0420)
If you are very sure about 1, 2, 3, 4 and 5 then target main oxygen sensor located after exhaust manifold and before catalytic converter. This oxygen sensor provides ECU feedback of the oxygen contents in the exhaust gas. The ECU uses this feedback to maintain proper air-to-fuel ratio. The main O2 sensor voltage should vary fairly rapidly between about 200mV and 800mV. After replacement disconnect battery positive terminal for a while and reconnect it. Start the car and see if Check Engine light turns on. Replacing oxygen sensor from the top requires 22mm or 7/8 slotted socket, but, still can be replaced with precision by 22mm open-end line wrench accessing from bottom.
If Check Engine light turns on. After a while, replace sub oxygen sensor (DTC code: P0421) located after catalytic converter and before exhaust tail pipe. This sub-oxygen sensor is slower in response than main one and does not contribute to air-to-fuel ratio. However, ECU uses this feedback for proper functioning of catalytic converter. This sub-oxygen sensor should hold fairly steady around 500mV. After replacement disconnect battery positive terminal for a while and reconnect it. Start the car and see if Check Engine light turns on after a while target following sensors in sequence.
7. Defective Manifold Absolute Pressure (MAP) sensor.
8. Defective Engine Coolant Temperature (ECT) sensor.
99.9% your problem will be solved at either step 4, step 5 or at step6.
The purpose is served, if it can save your expensive charges for autoshop diagnosis.
I am posting this because some one posted very helpful list of OBD-II codes for ready refence and othe community member supplied me information what I was looking for. Personally, I found this community :whatwhat: GREAT!!!:clap:
For every motorist it is most annoying :sosad: if “CHECH ENGINE” yellow light pops-up while driving along. It is the most misunderstood indicator on your dashboard, the "check engine" light can mean many different things, from a loose gas cap to a seriously malfunctioning engine loosing power.
You do not have to pull the car over to the side of the road and call a tow truck. Still you can drive your car safely. But, you should get the car checked professionally for engine relate fuel system, cooling system, exhaust system, EGR system and EVAP system, as soon as possible. Ignoring this warning, may lead you end up damaging engine or degrading performance by loosing fuel economy and emitting higher levels of pollutants.
Here are some simple steps for Do-It-Yourself….
Just simply do not throw parts one-by-one, make sure it is faulty before you replace. If you do not know how to check particular component, ask :ugh3: , some one will definitely help you out here.
In Toyota Corolla, there are certain sensors inputs to ECU Engine Control Unit which can trigger "Check Engine". These are....
Engine coolant Temperature sensor
Mass Air flow sensor
Crank shaft Position Sensor
Throttle position sensor
Park / neutral gear Selector Position
Vehicle Speed Sensor
Knock Sensor
Power steering Oil Pressure
Intake Air Sensor
Fuel / Vapor Pressure
Absolute Manifold Pressure
Oxygen / Air-fuel Ratio Sensor
EGR –Flow / Temperature Sensor
If you can start and steer your car well and smoothly from extreme right and left, but, still inspect for power steering fluid loss or leakage. If, still Check Engine light remains on you should target last three sensors. Possible causes are:
1. improper fuel pressure.
Leak in fuel system, may be pin-hole, To detect this fill-up your tank to the maximum, park your car in a clean space for a while 5 to 10 min. and check the for the fuel leak on the bottom, if there is any, may be because of loose Gas Cap, Fuel intake pipe, Gas Tank or Fuel lines.
2. Leak in Exhaust system. Can be detected and fixed very easy.
3. Fuel injector restricted. Use Fuel Injector Cleaner several times.
4. Engine coolant Temperature sensor (DCT Code : P0115)
Check Engine Cooling Sytem and radiator circuit for any possible leakage.
Inspect Radiator and hoses connection for leaks. Keep checking level of radiator coolant very often. If there is no leak...
A thermistor built into the engine coolant temp. sensor changes the resistance value according to the engine
coolant temp.
DTC - P0115 Open or short in engine coolant temp. sensor circuit
-Open or short in engine coolant temp. sensor circuit
-Engine coolant temp. sensor
Follow these steps.
(a) Disconnect the engine coolant temperature sensor connector.
(b) Connect the terminals 1 with 2 of the engine coolant temperature
sensor connector. Measure the resistance between terminal 1 and 2. check for open circuit or short circuit. Ideally it should read between 2.0 Kohms to 3.0 Kohms.
(c) Turn the ignition switch ON. Start the vehicle.
(d) Measure the resistance between terminal 1 and 2. As the coolant temperature starts rising up, the resistance starts falling down. At 180 deg C it should read approximately 0.2 Kohms, depends on make.
If the ECM detects the DTC P0115, it operates fail safe function in which the engine coolant temperature is assumed to be 80_C (176_F).
5. EGR – Exhaust Gas Recycle (DTC Code: 71 or P0401)
EGR system reduces NOx output by re-circulating portion of exhaust gases with normal air-to-fuel charge in the engine. EGR Flow is higher while cruising and mid-range acceleration when typical combustion temperature is very high. At lower speed and light load condition lower EGR flow is required. No EGR flow is required while idling or engine warm-up. There are four major components in EGR system, EGR Valve, EGR Vacuum Modulator, VSV: ECU controlled Vacuum Switching Valve and EGR Gas Temperature Sensors plus piping. With the age of the vehicle, EGR system problem is very common.
Use this routine:
-Remove the EGR Vacuum Modulator from the holding clamp and open the top cap. Inspect and replace the filter if required. Diesel (without any rust inhibitor additives or contents) can be used for removal of carbon deposits in the piping.
-Remove the EGR Valve from the mount. Remove the EGR inlet and outlet pipes from the exhaust manifold and the intake manifold. Blow air in inlet port and check for external and internal leaks. Inspect and replace the gasket if required. Inspect the manifold EGR ports and the EGR inlet and outlet pipes for a blockage caused by excessive deposits, casting flashing or other damage. Diesel (without any rust inhibitor additives or contents) can be used for removal of carbon deposits in the piping (A heavy guitar string on a drill motor works real good for running thru the manifold passage to open up the port). Then re-install the EGR and road-test again and also try cruise control at various speeds. If the light doesn't come on, you know that was the problem.
-Check EGR Temperature Sensor.
- Check and clean inlet and out let ports plus electrical connector of EGR VSV. ECU uses three signals to control the operation of EGR VSV switch --- distributor signal, coolant temperature signal and vacuum pressure signal. So after carrying out EGR system maintenance, you should service clean up for distributor cap and clan up electrical contacts of distributor, engine coolant temp sensor and vacuum sensors.
Again, with the age of the vehicle, this is very common.
6. Defective heated Main oxygen sensor No. 1. (DTC code: P0130, P0133, P0420)
If you are very sure about 1, 2, 3, 4 and 5 then target main oxygen sensor located after exhaust manifold and before catalytic converter. This oxygen sensor provides ECU feedback of the oxygen contents in the exhaust gas. The ECU uses this feedback to maintain proper air-to-fuel ratio. The main O2 sensor voltage should vary fairly rapidly between about 200mV and 800mV. After replacement disconnect battery positive terminal for a while and reconnect it. Start the car and see if Check Engine light turns on. Replacing oxygen sensor from the top requires 22mm or 7/8 slotted socket, but, still can be replaced with precision by 22mm open-end line wrench accessing from bottom.
If Check Engine light turns on. After a while, replace sub oxygen sensor (DTC code: P0421) located after catalytic converter and before exhaust tail pipe. This sub-oxygen sensor is slower in response than main one and does not contribute to air-to-fuel ratio. However, ECU uses this feedback for proper functioning of catalytic converter. This sub-oxygen sensor should hold fairly steady around 500mV. After replacement disconnect battery positive terminal for a while and reconnect it. Start the car and see if Check Engine light turns on after a while target following sensors in sequence.
7. Defective Manifold Absolute Pressure (MAP) sensor.
8. Defective Engine Coolant Temperature (ECT) sensor.
99.9% your problem will be solved at either step 4, step 5 or at step6.
The purpose is served, if it can save your expensive charges for autoshop diagnosis.
I am posting this because some one posted very helpful list of OBD-II codes for ready refence and othe community member supplied me information what I was looking for. Personally, I found this community :whatwhat: GREAT!!!:clap:
