Fuel light flashes, check engine light on

My car has recently developed an issue with the fuel light that started flashing for no apparent reason. This occurs while I'm driving with about half of gas tank or more. The fuel light starts to flash, which is followed by the check engine light coming on as well. I had the fuel cap replaced. What might cause this?
Experienced mechanics share their insights in answering this question :
Hi there, thanks for writing in about your 1997 Mercedes-Benz S420. The fuel light circuit receives information from the fuel level sending unit to show the approximate fuel level and give a warning as the level becomes low. There can be a malfunction in the sending unit circuit or the circuit for the lighting. I recommend having an experienced technician diagnose the warning lights in order to make the appropriate repairs.

How to Identify and Fix Common car Problems ?

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The Gas Cap Trick

Sometimes, a loosened or cracked gas cap is the culprit of a triggered check engine light. This typically happens because of the fumes that are released. Simply remove your gas cap and put it back in place. Turn your car on, and the engine light may already be reset.

The check engine light alert may indicate a problem with the engine management system, the fuel injection system, the exhaust system, the ignition system, or the fuel system. Any of these problems might trigger the engine to enter emergency mode.
A loose gas cap will not only let in dirt and grime, but it can also allow fuel vapors to escape. These vapors can trigger an error in the emissions system, which would light up the check engine light.
2014 Mercedes-Benz GL 450 Check Engine Light Flashing

Other mainly common reasons for a Check Engine Light are damaged oxygen sensor, broken head gasket, dirty mass airflow sensor, broken emissions control part, a malfunction with the fuel injection system, or broken spark plugs to name a few.

Fuel System Issues

Something as simple as forgetting to replace the gas cap could cause your “check engine” light to come on. This is because the gas cap keeps vapors from escaping the fuel tank. A loose or broken gas cap can dramatically reduce fuel efficiency and increase emissions.

What the fuel cap indicator means. Simply put, if your fuel cap light is on, it means that the computer has detected a leak in the system, typically from a loose gas cap. If this light comes on while driving, pull over in a safe spot and re-secure the cap.
Press the lower right button on the left side of your steering wheel, and again it will show the reason why the “check engine” light is on. Find the reset button on the left side of your instrument cluster. Press the reset button and hold it until your display shows “To reset: Press reset button for 3 seconds.”
In most cases, your Mercedes-Benz light will go off after about 20-40 miles. If you drive over that amount and the light is still on, you will need to bring it in to Park Place so the light and code can be double-checked and reset.
While the check engine light can definitely be indicative of serious problems, the most common cause of the flashing is usually an engine misfire. There are many reasons why an engine misfire might be occurring. To run smoothly, an engine must be receiving the correct amount of power from the cylinders in your vehicle.
A solid check engine light indicates a problem that needs to be addressed but is typically not urgent. A flashing check engine light indicates a severe problem that requires immediate attention to avoid further damage.
In most cases, successfully repairing the issue that caused your light to come on will cause the check engine light to turn off automatically—but only after 10 to 20 “cycles”.
The check engine light should go off after you drive for several minutes if the light was caused by a loose gas cap. Pay attention to the dashboard after the check engine light experience. If you find that the light keeps coming on, and goes off again once you tighten the gas cap, then your gas cap is too loose.
In most cases, successfully repairing the issue that caused your light to come on will cause the check engine light to turn off automatically—but only after 10 to 20 “cycles”.
A loose gas cap will not only let in grime and dirt, but it can allow fuel vapors to escape the fuel tank. These vapors can produce an error in the emissions system, which could cause the check engine light to illuminate.
In most cases, successfully repairing the issue that caused your light to come on will cause the check engine light to turn off automatically—but only after 10 to 20 “cycles”.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Fuel light flashes, check engine light on
ANSWER : Hi there, thanks for writing in about your 1997 Mercedes-Benz S420. The fuel light circuit receives information from the fuel level sending unit to show the approximate fuel level and give a warning as the level becomes low. There can be a malfunction in the sending unit circuit or the circuit for the lighting. I recommend having an experienced technician diagnose the warning lights in order to make the appropriate repairs.

Check engine light refuses to go off after engine replaced
ANSWER : Hello there, you have a long series of issues going on with your 2013 Hyundai Sonata. If you keep getting a repeating oil light on than there is likely a fault in that system.

Since this fault has lasted after the engine was replaced it could be a oil pressure sensor, wiring harness fault, ECU fault, oil pump, oil strainer clogged, or low oil pressure.

To diagnose this issue properly you need a complete vehicle inspection to start from square one and identify the root cause of all this.

While driving on freeway truck goes into a limp mode, and the check engine light, abs light, parking break light, service brake
ANSWER : It is possible that you could be having an issue with your powertrain control module. This is somewhat of a common problem on many GM vehicles. I would recommend having your vehicle inspected by the dealership to determine if the powertrain control module is functioning properly. If not, a reflash of the powertrain control module may resolve the issue but often times it must be replaced.

Car started to slow down and then the check engine light, battery, and engine oil light came on. What could cause this?
ANSWER : Hi there. It is possible that the battery cable came loose or the wires to the oil pressure sensor has came loose or failed. Check the battery cables and make sure that the terminals are tight and clean. Check the wires to the oil pressure sensor and make sure that they are connected and not broken. If everything looks good, then the oil pressure sensor may have failed. Plus, check the computer for codes and see what is stored. This will lead you to the part that could have failed. I recommend replacing the oil pressure sensor then checking to see if the lights will go out. If you need further assistance troubleshooting your vehicle, then seek out a technician, such as one from Your Mechanic, that can assist you with the warning lights that came on.

2006 Ford Mustang has check engine light on
ANSWER : There are countless potential causes for your illuminated check engine light. The mechanic manually turned off the light, but it came back on because the problem has not been fixed. The first place to start is retrieval of the stored diagnostic trouble codes (DTCs). These codes serve as a starting point for any further diagnostics a mechanic may perform. Codes will be stored anytime the check engine light is on. Since the first mechanic was unable to fix your concern, I recommend giving the professionals at YourMechanic a call. We offer expert check engine light diagnosis and repair.

Car goes into limp mode when the check engine light and VSA light comes on
ANSWER : The lights that you have on and the vehicle going into fail safe mode is an indication you have a major system failure that will require computer to be tested for codes first. There are many possible codes it can be so the additional testing will be needed to isolate the cause of the problem.

After i replace my whole fuel pump will that solve battery and security and oil light and. Check engine service light problem
ANSWER : If a faulty fuel pump caused the engine to abruptly stop, you might see a variety of warning lights. Once the engine is running again, the lights may go out but ONLY if the warning lights were related to the fuel pump failing. For example, if the oil pressure warning light was on while the engine was still running, it likely that that light will remain on even after installing a new fuel pump. Of course, if the oil pressure warning light does comes on, stop the engine immediately to avoid damage. Without downloading the diagnostic trouble codes that have caused the check engine light to come on, it is hard to say if the check engine light will turn off after the pump is replaced because the codes that have set (causing the light to come on) may pertain to the fuel pump but could pertain to other issues, as well. So, this cannot be answered without downloading those codes.

Of course, if your car is not running be sure that you very carefully diagnose the cause because you don’t want to end up needlessly replacing the fuel pump when indeed the actual problem lies elsewhere including perhaps just a bad electrical connection to the fuel pump if you are seeing no pump operation. Given what you are describing, I recommend that you request a no start diagnostic and the responding certified mechanic will determine if you actually need a fuel pump and, as well, let you know why the warning lights are on and what repairs, if any, are needed. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Traction light/reduced engine power and check engine light coming on
ANSWER : Hello. From what you describe, it would appear that your vehicle may be experiencing some sort of intermittent wiring or sensor issue. If the problem occurred again after driving over a bump, then it may be possible that a damaged or loose wire is shorting or having contact issues. A common issue that can cause stalling is a faulty crank position sensor or wiring. I would carefully examine the engine for any loose or damaged wires. If the Check Engine Light comes back on, I would recommend having the trouble codes scanned before resetting the computer.