Check engine light comes on intermittently

I don't know what vehicle this is, but it is not uncommon for the inter-module communications system (links between computer modules in the vehicle) to have an intermittent problem ("hiccup") due to a voltage transient, which can set all sorts of DTCs. If this is the case, restarting the vehicle will reset all modules but will hold history DTCs in the ECM. Reset the codes with a code scanner, and periodically monitor the ECM with it to see if you have an ongoing problem.

That is your "Check Engine Light" / "Service Engine Light". It means the Computer (ECM / PCM / ECU, it goes by many names) has detected a problem with one or more parts on the engine or transmission.
The easiest way to find out, is to stop by an auto parts store (like Advance Auto, Auto Zone, etc) and have them hook up a Scan Tool to read the Trouble Codes from the ECM. They do that for free. Most if not all garages/mechanics also have the necessary Scan Tool as well, but most of those will charge you just to read the codes.

Yes, water could be in the gasoline. Try to run a few tanks of gas through it to clear up that problem.

Are there any engine codes on this car that are readable? Maybe a throttle position sensor is not giving good data to the computer.

BASIC TROUBLESHOOTING

1. NOTE: The following explains how to activate the Trouble Code signal light in the instrument cluster. Before suspecting the C-4 or CCC system, or any of its components as being faulty, check the ignition system (distributor, timing, spark plugs and wires). Check the engine compression, the air cleaner and any of the emission control components that are not controlled by the ECM. Also check the intake manifold, the vacuum hoses and hose connectors for any leaks. Check the carburetor mounting bolts for tightness. NOTE: For information regarding computer control/troubleshooting of the Electronic and Digital fuel injected vehicles, please refer to Section 5 of this manual. The following symptoms could indicate a possible problem area with the C-4 or CCC systems:
   1. Detonation
   2. Stalling or rough idling when the engine is cold
   3. Stalling or rough idling when the engine is hot
   4. Missing
   5. Hesitation
   6. Surging
   7. Poor gasoline mileage
   8. Sluggish or spongy performance
   9. Hard starting when engine is cold
   10. Hard starting when the engine is hot
   11. Objectionable exhaust odors
   12. Engine cuts out
   13. Improper idle speed (CCC only). As a bulb and system check, the Check Engine light will come on when the ignition switch is turned to the ON position but the engine is not started. The Check Engine light will also produce the trouble code/codes by a series of flashes which translate as follows: When the diagnostic test lead (C-4) or terminal (CCC) under the instrument panel is grounded, with the ignition in the ON position and the engine not running, the Check Engine light will flash once, pause, and then flash twice in rapid succession. This is a Code 12, which indicates that the diagnostic system is working. After a long pause, the Code 12 will repeat itself two more times. This whole cycle will then repeat itself until the engine is started or the ignition switch is turned OFF. When the engine is started, the Check Engine light will remain on for a few seconds and then turn off. If the Check Engine light remains on, the self-diagnostic system has detected a problem. If the test lead (C-4) or test terminal (CCC) is then grounded, the trouble code will flash (3) three times. If more than one problem is found to be in existence, each trouble code will flash (3) three times and then change to the next one. Trouble codes will flash in numerical order (lowest code number to highest). The trouble code series will repeat themselves for as long as the test leads or terminal remains grounded. A trouble code indicates a problem with a given circuit. For example, trouble code 14 indicates a problem in the cooling sensor circuit. This includes the coolant sensor, its electrical harness and the Electronic Control Module (ECM). Since the self-diagnostic system cannot diagnose every possible fault in the system, the absence of a trouble code does not necessarily mean that the system is trouble-free. To determine whether or not a problem with the system exists that does not activate a trouble code, a system performance check must be made. This job should be left to a qualified service technician. In the case of an intermittent fault in the system, the Check Engine light will go out when the fault goes away, but the trouble code will remain in the memory of the ECM. Therefore, if a trouble code can be obtained even though the Check Engine light is not on, it must still be evaluated. It must be determined if the fault is intermittent or if the engine must be operating under certain conditions (acceleration, deceleration, etc.) before the Check Engine light will come on. In some cases, certain trouble codes will not be recorded in the ECM until the engine has been operated at part throttle for at least 5-18 minutes. On the C-4 system, the ECM erases all trouble codes every time that the ignition is turned off. In the case of intermittent faults, a long term memory is desirable. This can be produced by connecting the orange connector/lead from terminal S of the ECM directly to the battery (or a hot fuse panel terminal). This terminal must always be disconnected immediately after diagnosis as it puts an undue strain on the battery. On the CCC system, a trouble code will be stored until the terminal R at the ECM has been disconnected from the battery for at least 10 seconds. Fig. 1: C-4 system diagnostic test lead location - above ECM Fig. 2: Under dash test terminal location
       Fig. 3: CCC system diagnostic test terminal located underneath the left side of the instrument panel

This sounds like the check engine light, it is safe to drive the car, but read about what causes this light to come on below. U can have any Kragen auto test the system for free.
Why my Yellow Check Engine is on?
The engine computer or PCM/ECM

All modern vehicles have a computer or the ECM (Electronic Control Module) that controls the operation of the vehicle powertrain (the engine and transmission). The main purpose of this is to keep the engine running at top efficiency with the lowest possible emissions. With constantly growing demands for better fuel economy and new strictest emission regulations it's not very easy to achieve. The engine parameters need to be constantly and precisely adjusted according to various conditions such as speed, load, engine temperature, gasoline quality, ambient air temperature, road conditions, etc. That's why today's cars have much more electronics than in early days - there is a large number of various sensors and other electronic devices that help the vehicle computer or ECM to precisely control the engine and transmission operation and monitor emissions.
The vehicle computer system has self-testing capability. When the computer senses that there is a problem with some of the components it stores the correspondent trouble code(s) in its memory and lights up the "Check Engine" or "Service Engine Soon" light to tell you that there is a problem and your car needs to be looked at. To properly diagnose what is wrong, you need to take your car to a mechanic or a dealer. The technician at the dealership or a garage will then hook up the scanner to the car computer and retrieve the stored trouble code(s). Then he (she) will look it up in the service manual provided by a car manufacturer. The service manual contains the list of possible codes (about few hundreds) and describes what each code means and what needs to be tested. The code itself doesn't tell exactly what component is defective - it only indicates where to look, what engine parameter is out of normal range. The technician will have to perform further testing to pinpoint a defective part.

Why my Check Engine/Service/Check Engines Soon light comes on?
The engine computer or PCM/ECM
All modern vehicles have a computer or the ECM (Electronic Control Module) that controls the operation of the vehicle powertrain (the engine and transmission). The main purpose of this is to keep the engine running at top efficiency with the lowest possible emissions. With constantly growing demands for better fuel economy and new strictest emission regulations it's not very easy to achieve. The engine parameters need to be constantly and precisely adjusted according to various conditions such as speed, load, engine temperature, gasoline quality, ambient air temperature, road conditions, etc. That's why today's cars have much more electronics than in early days - there is a large number of various sensors and other electronic devices that help the vehicle computer or ECM to precisely control the engine and transmission operation and monitor emissions.
The vehicle computer system has self-testing capability. When the computer senses that there is a problem with some of the components it stores the correspondent trouble code(s) in its memory and lights up the "Check Engine" or "Service Engine Soon" light to tell you that there is a problem and your car needs to be looked at. To properly diagnose what is wrong, you need to take your car to a mechanic or a dealer. The technician at the dealership or a garage will then hook up the scanner to the car computer and retrieve the stored trouble code(s). Then he (she) will look it up in the service manual provided by a car manufacturer. The service manual contains the list of possible codes (about few hundreds) and describes what each code means and what needs to be tested. The code itself doesn't tell exactly what component is defective - it only indicates where to look, what engine parameter is out of normal range. The technician will have to perform further testing to pinpoint a defective part

Why my Check Engine/Service Engines Soon light comes on?
The engine computer or PCM/ECM
All modern vehicles have a computer or the ECM (Electronic Control Module) that controls the operation of the vehicle powertrain (the engine and transmission). The main purpose of this is to keep the engine running at top efficiency with the lowest possible emissions. With constantly growing demands for better fuel economy and new strictest emission regulations it's not very easy to achieve. The engine parameters need to be constantly and precisely adjusted according to various conditions such as speed, load, engine temperature, gasoline quality, ambient air temperature, road conditions, etc. That's why today's cars have much more electronics than in early days - there is a large number of various sensors and other electronic devices that help the vehicle computer or ECM to precisely control the engine and transmission operation and monitor emissions.
The vehicle computer system has self-testing capability. When the computer senses that there is a problem with some of the components it stores the correspondent trouble code(s) in its memory and lights up the "Check Engine" or "Service Engine Soon" light to tell you that there is a problem and your car needs to be looked at. To properly diagnose what is wrong, you need to take your car to a mechanic or a dealer. The technician at the dealership or a garage will then hook up the scanner to the car computer and retrieve the stored trouble code(s). Then he (she) will look it up in the service manual provided by a car manufacturer. The service manual contains the list of possible codes (about few hundreds) and describes what each code means and what needs to be tested. The code itself doesn't tell exactly what component is defective - it only indicates where to look, what engine parameter is out of normal range. The technician will have to perform further testing to pinpoint a defective part.

Why my Check Engine/Service Engines Soon light comes on?
The engine computer or PCM/ECM
All modern vehicles have a computer or the ECM (Electronic Control Module) that controls the operation of the vehicle powertrain (the engine and transmission). The main purpose of this is to keep the engine running at top efficiency with the lowest possible emissions. With constantly growing demands for better fuel economy and new strictest emission regulations it's not very easy to achieve. The engine parameters need to be constantly and precisely adjusted according to various conditions such as speed, load, engine temperature, gasoline quality, ambient air temperature, road conditions, etc. That's why today's cars have much more electronics than in early days - there is a large number of various sensors and other electronic devices that help the vehicle computer or ECM to precisely control the engine and transmission operation and monitor emissions.
The vehicle computer system has self-testing capability. When the computer senses that there is a problem with some of the components it stores the correspondent trouble code(s) in its memory and lights up the "Check Engine" or "Service Engine Soon" light to tell you that there is a problem and your car needs to be looked at. To properly diagnose what is wrong, you need to take your car to a mechanic or a dealer. The technician at the dealership or a garage will then hook up the scanner to the car computer and retrieve the stored trouble code(s). Then he (she) will look it up in the service manual provided by a car manufacturer. The service manual contains the list of possible codes (about few hundreds) and describes what each code means and what needs to be tested. The code itself doesn't tell exactly what component is defective - it only indicates where to look, what engine parameter is out of normal range. The technician will have to perform further testing to pinpoint a defective part

Why my Check Engine light comes on?
The engine computer or PCM/ECM
All modern vehicles have a computer or the ECM (Electronic Control Module) that controls the operation of the vehicle powertrain (the engine and transmission). The main purpose of this is to keep the engine running at top efficiency with the lowest possible emissions. With constantly growing demands for better fuel economy and new strictest emission regulations it's not very easy to achieve. The engine parameters need to be constantly and precisely adjusted according to various conditions such as speed, load, engine temperature, gasoline quality, ambient air temperature, road conditions, etc. That's why today's cars have much more electronics than in early days - there is a large number of various sensors and other electronic devices that help the vehicle computer or ECM to precisely control the engine and transmission operation and monitor emissions.
The vehicle computer system has self-testing capability. When the computer senses that there is a problem with some of the components it stores the correspondent trouble code(s) in its memory and lights up the "Check Engine" or "Service Engine Soon" light to tell you that there is a problem and your car needs to be looked at. To properly diagnose what is wrong, you need to take your car to a mechanic or a dealer. The technician at the dealership or a garage will then hook up the scanner to the car computer and retrieve the stored trouble code(s). Then he (she) will look it up in the service manual provided by a car manufacturer. The service manual contains the list of possible codes (about few hundreds) and describes what each code means and what needs to be tested. The code itself doesn't tell exactly what component is defective - it only indicates where to look, what engine parameter is out of normal range. The technician will have to perform further testing to pinpoint a defective part.

those lights will come on to make u aware that ecm has detected problems in abs and engine system,ecm has stored codes that will have to be read with an obd2 scan tool,codes will point to problem areas to check and repair!

Pull the code(s) at the moment the Check Engine light is flashing. Purchase an OBDII scanner (Auto Zone, Car Quest, O'Riely's, etc.) Be ready when it happens... do not shut off the engine ... plug the OBDII scanned into the DLC (Data Link Connector) and retrieve the code(s) at the moment it happens. If you still don't retrieve any codes when this happens, you have a malfunctioning ECM (Engine Control Module). Before you replace it (if this actually happens - no codes and Check Engine light is flashing), Disconnect both battery cables and touch them together for 30 seconds. Reconnect them to the battery and drive vehicle to see if it happens again (could be junk/corruption in ECM memory banks). If it happens again, the ECM is malfunctioning. REASONING: Whenever the "Check Engine" light comes on, there is ALWAYS a DTC (Diagnostic Trouble Code) stored in the ECM (Engine Control Module). If no codes are retrieved, there's only one cause - ECM MALFUNCTION!