Service Engine Soon

My 1999 Suburban 1500 service engine soon light comes on when i am climbing up hill at a constant speed. it generally resets itself about 1 day later. Does anyone have some help for me?

When the PCM sees a problem with the emissions system or its componants..it sets a trouble code and turns on the MIL (SES light)...If you can pull the code (some auto parts stores will do this for free) we can give you some ideas on what is going on

I've heard you can jump some connectors at the bottom of the dash to get a code. Is this true? I got a constant 'Service Engine Soon' light yesterday.

2000 Suburban.

that is true, you can pull the codes from under thedash on the drivers side. My problem has been corrected, came out with 2 misfires from injectors 3 and 5.

'99 has OBD2 diagnostics and you can't pull a code simply by grounding the aldl terminals like the older GM's. It requires an OBD2 code scanner. Autozone normally will read your codes for free. Let us know what it says before you go buying any parts.

I bought an ODBII scanner. I was told by Kragen that a parts store got sued because they misdiagnosed a problem so they dont check codes anymore. Anyways I got mine on sale for 129.99 + a $30 rebate. So pretty much $100. Is that a good price?

ANYWAYS.... I got a P0446 Code - Evaporative Emnissions Control System Vent Malfunction.

Ummm...Any help on this. I went off roading in some dunes a couple of days before I got the SES light.

Absolutely everything can and will cause a check engine light or SES light. From a loose gas cap (computer sees a pressure loss in the fuel tank) to a bad sensor or a bad computer (one that has no ability to make things happen or see fault codes the tech creates) , to a vacuum leak, a bad fuel pump, a bad spark plug, a plugged fuel filter or a broken, pinched or disconnected wire.

So when your check engine light or SES light comes on, the procedure is the same for all cars. Someone needs to pull the code, check the circuit, test a few sensors, see what’s going on and determine what it is the computer is really seeing and why it doesn’t like what it sees. I typically use a scanner to perform many of these tasks and the scanner will allow me to watch what’s going on. It will allow me to see what the coolant sensor, speed sensor, throttle position sensor is telling the computer. So as I watch the serial stream data, I should know if it is right or not. For instance, if I knew the engine was warmed up but I saw the coolant sensor was telling the computer the engine temperature was -40, I would know the connection at the coolant sensor was defective or the sensor was open. If I saw the coolant sensor was telling the computer the engine was 150F and I knew it was well over 220F, I would replace the sensor, clear the code and test drive the car to see if the code reset or the SES light came back on.