Check Engine Light

The check engine light (service engine soon) comes on and stays on when a problem is detected by the self diagnosis system of your vehicle. Generally, the problem is in the emissions or something that is affecting the effectiveness of the emissions, but other causes can trigger the light to come on, too. To determine the cause, the vehicle will need to be taken to a parts store or a shop that has an OBD2 scanner, or for 1995 and earlier models, an OBD1 scanner, While a scanner will not give you the magic answer, it will give you a code that narrows down the problem area.

can you tell me why my 1999-2000 Chevy trailblazer light is on

this happens to my 94 and after looking all over to find out why i traced it to the starter switch was broken and stuck between the ignition and off position just enough to start it but not enouph let the light go out

I would not think so but I have learned that nothing is impossible. P0040 is not an O2 sensor code, it is a EVAP system leak. A loose gas cap will set this code for sure as the code indicates a leak in the EVAP system. If it does not come back on then forget it. If it does replace the gas car first and clear the codes. If it comes back on then check the EVAP system hoses for cuts or leaks, check the purge valve. If none of these are leaking you need to see a pro and have a smoke test run. These can be very tricky to find at times.

quite possibly....the check engine light is a universal signal saying "something is wrong". Take the car to auto zone and have them use the hand held diagnostic. Once used, the diagnostic will pull up a code from the engine's computer that the auto zone employee can pull up. Once the code is looked up for that particular vehicle, itll tell you what the light came on for.

The check engine light indicates that the computer has detected a "fault". Use a code scanner to find out what the computer has detected, that is PROBABLY the reason the engine is running poorly.

Sometimes

It can be any number of things, from a loose gas cap to any of the systems and sensors on the engine that are monitored by the computer. You need to have the codes pulled up with a code scanner

Answer

Faulty: spark plug, spark plug wire, ignition coil, ignition module, fuel injector are the most common. Coolant leaking into a cylinder is another.

Internal engine problems such as burnt valve, broken valve spring, bent push rod, worn rings

Answer

this could be anything to do with the cylinder on your car. The plug, the wire, the cap, or the coil (whichever you have.) your best bet is to do a tune up on thecar and do all the plugs, wires, cap, and rotor. if you have a coil pack, try to change those. this is all i can say for now. if that doesn't work, ask the question again and give a little more detail on how the car is acting.

Technically speaking, cylinders do not "misfire": the spark plug causes a spark which causes the fuel to ignite which moves the cylinder, so it is the spark plug that may misfire. Given that, motor vehicle spark plugs may misfire due to any of a number of reasons, including watered-down or low-grade fuel, old and/or dirty oil, fouled spark plugs, clogged cylinders, insufficient oxygen to the plugs, poorly aligned cylinders, et al.

whats mean dtc P1700 on zafira Z18XE.thanks

the emission lights could be comming on because your catalytic converter is not working right.

WITH MY 98 CAVELIER,I FOUND THE VACUMN LINE TO THE MAP SENSOR

OFF AND I REPLACED IT. NEXT I WENT THROUGH THE GEARS,AND THE E.T.S. LIGHT WENT OUT.THE ENGINE CHECK LIGHT WAS STILL ON AND I

NOTICED I HAD THE LARGE HOSE "CARB TO AIR FILTER OFF" I INSTALLED IT AND THE LIGHT WENT OUT."IT HAS A SENSOR IN IT" SUMMARY IS THE CAR RUNS FINE. LOUIEBELLSON@COMCAST.NET

HERES A BETTER SOLUTION...

instead of wasting money that you don't need to, puh the button on the side of your shift knob. That's the ETS button. It will turn it on.

Then I guess you didn't check everything...;) Could be internal...there's no telling really unless a professional trouble shoots it. Or unless you have recently had an reoccuring problems and can elaborate either on those or on any noises you've had with the car recently. That's all I have with the lack of info unless you want to try resetting the ECU which would involve you disconnecting the battery, pumping your brakes, letting it sit for 10-15 min then reconnecting and starting her up. Good luck.

Try disconnecting the battery for a minute or 2 and then re-connect. This sometimes clears the codes in the engine control modules.

The engine computer has detected a malfunction and set a code.

Under the hood on top of the left fender. Take it to your dealer to be analyzed or go to your local auto parts store and they should have an analyzer to test the module beneath the steerin column.

check for vacuum leaks unplug the negative post on the battery terminal for about 15 minites

I had this problem on and off for over 1 1/2 years, until finally, last year, my local Toyota dealer fixed it, under warranty, repairs totaled over $1200.00! My Rav 4 is a 2001, but apparently it is a large issue because I jst received a notice from Toyota stating that there has been a problem with the system that involves the "Check Engine" light, and they requested my car be brought in, if I hadn't already done so - contact a local dealer ASAP!

if there is a auto zone around you take your car there they will do a dyno test on it for free i had a problem with my car that the light would not go off and i had a lose hose that was causing the problem did you put fuel injector fluid in your car to make sure the fuel injector wasn't dirty?

obd 2 systems can be very complicated, and once the code is triggered, it will stay in the ecu til its erased, a friend of mine was running into the same problems it turned out to be her gas cap which wasnt tightened correctly, and threw the code and it stayed there til it was erased, try disconnecting your battery, and see if it clears. if Honda did the reapirs, take it back to them and make them fix it.

By the way, if you enjoy modding you car, like i do, the check engine light may come on after doing work on your car. For instance, today, i put a short RAM intake on my 1999 Honda Accord EX-L V6. After completing the install, i unplugged the sensors and turned on the car for a sec to let it know that it should recalculate the air intake. I then reconnected the sensors and turned the car on. I let it idle for a while so it could recalibrate. After doing all this, I realized the check engine light, or malfunction light was on. I understood that this was because i had been tinkering, and of course i didn't want to pay $80 for a diagnostic, which would turn off the light. What i could have done, is wait, and after 40 startups with no problem the light would have turned off. Alternatively, what i did was REMOVE THE NUMBER 13 FUSE FROM THE FUSE BOX ON THE PASSENGER DOOR FRAME FOR 10 SECONDS AND THEN REPLACE IT. THIS WILL MAKE YOUR MALFUNCTION/CHECK ENGINE LIGHT GO OFF BUT THIS IS NOT RECOMMENDED AND I DON'T TAKE ANY RESPONSIBILITY IF YOU RUIN YOUR CAR. THAT LIGHT USUALLY DOESN'T LIGHT UNLESS THERE IS A PROBLEM. IF THE LIGHT COMES BACK ON AFTER A WHILE YOU SHOULD TAKE YOUR CAR TO A QUALIFIED TECHNITIAN BECAUSE SOMETHING IS REALLY <EXPLETIVE>'ED UP!

get the CEL checked and fix the problem. Disconnecting the battery for 15 minutes will reset the light on an OBD1 vehicle.

if no one knows go to google.

There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.

It is below the injection pump, in the back of the timing cover.