The engine light in the 2004 Envoy stays on and the reduced engine power light

SOURCE: SES light then Reduced engine power light, loss of engine power

Hi It me Mohammad Siddiq my dear. First of all it will be wise of use to take your vehicle to a dealership or any other fully equipped w/shop. They can better tell you what the fault your vehicle has. But at the same time if your friend has the same model vehicle so you can exchange some parts with that vegicle, e.g., Mass Air Flow or TPS (Throttle Position Sensor) and can check your vehicle. These parts do not need to be programmed with scan tool. Just Simply replace these parts and switch on the ignition and wait for 01 minute, then switch off for 30 seconds and then start the engine. Now road test your vehicle, if no SES light or reduced power then there was fault with the part/s replaced. So Return those parts and now you must replace these parts with new or used ones. Anything else I may be contacted on my yahoo id [email protected]. Thanks. I am an auto technician and working in a GM dealership in Saudi Arabia. I am from Pakistan.

SOURCE: 95 Lexus ES 300 check engine light is on and the overdrive off light is flashing

chances are you don't have to replace the computer. the reason i tell you this is because you did not mention that the car is running lousy. no complaints of rough idle or missfire or hard starting. chances are that your engine speed sensor which sends the signal to the computer which then controls the transmission is most likely the culprit.. and it could just bhe that there is a loose connection between the two. if that is ok then your transmission control module is faulty. this is not the main computer, but the gobetween the trans and the ecm.. hope this helps please rate this...thanks(btw....the knock sensors control timing not the trans mission)

SOURCE: Check Engine Light?

there are 3 one on each side of eng. on the Y pipe one behind the cat. convertor. not to hard change

SOURCE: 2001 Elantra stall, loss of power. Driving at

I am having the exact same problem with my 2001 Hyundai Elantra. I was told that the engine code that comes up when the sensor is on is called "Absolute Pressure In The Manifold". I was told by a "Hyundai Specialist" that when that code comes up it usually means that the seal on the manifold is Fuct. When my mechanic checked that out for me he had noticed that my manifold had 4 cracks in it(can varify cause he showed me). He replaced the manifold and gasket. The car ran fine for about 2-3 days and since then the problem has since come back and my check engine light will no longer go on/off it only stays on. Because of the check engine light always staying on I have noticed that on many occasions my car will hiccup many times in a row. The only way to stop the hiccup I have noticed is to take my foot right of the gas for approx. 2-3 sec then car will continue without hiccup(till it happends all over again). All in all I have been having this problem now for approx. 1 year and if there is somehow someway it could be repaired I would appretiate it.

SOURCE: 98 Nissan Maxima - Check Engine Light, Knock Sensor

If the car is pinging you will set a knock sensor code.'
This comes from bad gas and running lean., You really need this professionally inspected to rule out the basics. I have seen alot of nissans with the knock sensor code stored but the light is still off.
Fill up the tank with high octane chevron and some techron injector cleaner and clear the light. If it stays off for a couple days then go get it inspected. Even if the code is stored it will still pass as long as the light is still off and the monitors have run.