BMW Service Engine Soon Light On Problem

BMW Check Engine Light Problem & Solutions

Last Updated on Wednesday Apr 04, 2018

In this guide, we will go over the most common causes that trigger BMW Check Engine Light  (CEL) and how you can diagnose and reset this light yourself

Back to top

1. What does BMW Check Engine Light mean?

bmw service engine light soon check engine visit shop warning on instrument cluster

If your BMW check engine or service engine soon light turns on it means that there is a malfunction with the emission system or the engine itself. When BMW service engine soon light stays on, it means the Digital Motor Electronics DME (BMW term for Engine Control Unit - ECU) has detected a problem you will need to read the fault codes

Service Engine Soon (SES) and Check Engine Soon Light (CEL) on a BMW will come on if the Digital Motor Electronics DME detects a problem with engine's operation or emission system. When engine warning light stays ON constantly, it means there is a Diagnostic Trouble Code (DTC) present in the system.

bmw check engine light on service engine soonDon't panic! It doesn't mean your BMW needs to be towed unless the car is overheating or if the check engine light is flashing. The good news is that you can read the codes yourself without spending a fortune. Often the issue is not as serious as you may think.

Follow the steps below to diagnose BMW CEL yourself. It is important to read the codes as soon as possible. Ignoring a flashing CEL or SES light can lead to more serious and costly problems down the road.

Back to top

2. What to do when BMW check engine light turns on? 

The first step is to check the fuel cap. Tighten it until you hear it click. If the cap is loose it will trigger the CEL. If you believe the gas cap is the problem, retighten or replace the gas cap and drive the car as normal. Within two to three days the check engine light will turn itself off. No need to clear codes or use a scanner for a loose gas cap. If the light stays on, you need to read the codes. 

bmw loose gas cap



Most 2005 and newer BMWs will also show a separate symbol to remind you if you forget to tighten the fuel cap. If the gas cap was loose and you tighten it. The CEL light will reset itself in a few driving cycles, typically within a day or two.

If the BMW drives fine, closely monitor the engine temperature and make sure the oil light isn't staying on. If your BMW is overheating or oil light is on, stop driving your BMW immediately. Get the BMW towed if necessary.

Next, you need to read fault codes.

bmw obd2 port locationThis is a simple procedure you can perform yourself. One option is to use a cheap generic OBD2 code reader but keep in mind that a generic OBD2 code reader will not provide details as would an OBD2 scanner that is designed to read BMW specific fault codes. A generic code reader will provide generic fault codes that don't translate properly for BMW. Several auto parts stores such as Advance Auto Parts and Autozone may read the codes free of charge. Once you retrieve the code, do online research to find what that code means on BMW.

If the codes retrieved from the generic OBD2 scanner don't provide enough information you will need to read the fault codes with a BMW scan tool. One option is to take your BMW to an auto repair shop that specializes in BMW or buy a BMW scan tool and perform the procedure yourself

Back to top

3. How to reset BMW check engine light

These instructions show you how to read and clear codes related to check engine light on a BMW. In this guide, we use two of the most popular BMW scan tools. Of course, these are not the only scanners that can diagnose BMW check engine light. To learn more about various scanners read this article on Choosing the Best OBD2 Scanner for BMW.

Read BMW check engine codes using Foxwell NT510 for BMW

What we used:   Foxwell NT510 for BMW

Read DTC fault codes using BMW Carly for BMW

In this guide, we use a Level 2 OBD2 Scanner that can read BMW specific fault codes from the DME module. A BMW scan tool will provide a better description of the fault code and even display fault codes that may not be picked up by a generic OBD2 scanner. 

What we used:

  1. Carly for BMW adapter
  2. Carly for BMW App

Read fault codes using a generic scanner

check bmw fault codes

In this section, you will learn how to use a generic OBD2 scanner some of which cost as little as $15 to read BMW fault codes.

What you need:

  • Generic OBD2 scanner.
    • Even a $15 OBD2 scanner or an ELM327 Bluetooth adapter that pairs with your phone is able to read codes related to the check engine light. Once you retrieve the code, perform an online search to find out what it means for BMW. 


  1. Determine the status of check engine light on the instrument cluster. 
  2. Locate OBD2 port on your BMW. The port is under the dash on driver's side. 
  3. Plug scanner into the OBD2 port. Turn on ignition by pressing the start button without pressing on the brake pedal. 
  4. Allow the scanner to turn on. Press read/enter to read codes. Write down the codes and clear them once you are completed. 

This procedure only allows you to read and clear codes from the ECU / DME / DDE. If you have other problems a generic OBD2 scanner will not be able to read and clear the codes. In other words, generic OBD2 scanner are only able to read and clear codes from the ECU but not form other modules including ABS, SRS, Airbag, DSC, Stability Control, EGS Transmission etc. 


Note that you can read the codes, but you can't permanently clear them unless you fix the problem that triggered the code. If you don't fix the underlying problem the codes light will return. In some cases, it returns right away, in other cases it can take a day or two.

Back to top

4. Various BMW CEL Symbols

There is a  difference between BMW Check Engine Light vs. Service Engine Soon



  • Check Engine Light - Yellow CEL 
    • Engine Block Symbol in Dashboard
    • Problem is often minor such as loose gas cap
    • Often BMW drives fine
bmw service engine soon light


  • Service Engine Soon - SES Light
    • SES light doesn't always mean there is a major engine problem. 
    • BMW may run and drive fine. 
    • Don't ignore this light. Read BMW fault codes.
  • Check Engine Light - Half Yellow
    • Means problem is more severe. 
    • Car usually goes into limp mode to prevent further damage. 
    • Serious engine or transmission problem
    • BMW may be stuck in gear, Limp Home Mode
Back to top

5. Check Engine Light Flashing

If the check engine light is flashing, generally means that the DME module has detected a misfire. If the light is flashing you will notice poor acceleration, BMW engine shaking. This problem is often caused by bad spark plugs or bad ignition coil which is a common problem with many BMWs including 1, 3, 5, 6, X1, X3, X5 series. Other possibilities include vacuum leak, bad mass air flow sensor, clogged catalytic converter and blown a head gasket. It is not recommended to drive a BMW if the service engine light is flashing. When BMW service engine soon light is flashing and car is shaking you have a problem that needs to be addressed as soon as possible. 

Under these conditions, your BMW will be very sluggish and the motor will shake at idle. The problem is often caused by a bad ignition coil or spark plug. Read the codes as soon as possible and fix the underlying problem. 


Do not continue to drive a BMW with flashing check engine light for an extended distance. Driving a BMW with check engine light flashing, engine shaking can cause expensive damage to other components including the catalytic converter.

Back to top

6. Cost to diagnose BMW check engine light

bmw check engine light service engine soon repair cost

The typical cost to diagnose BMW check engine light can vary from $60-$130. BMW dealerships generally charge one-hour diagnostic. Shops that specialize in BMW may charge only 30 minutes of labor. A few BMW shops may even scan your BMW CEL codes free of charge. During this procedure, an auto technician will plug a diagnostic scanner into the OBD2 port and read the codes from the DME DDE module. You can perform the same procedure yourself by using an OBD2 scanner that can read BMW specific fault codes

Back to top

7. Common Symptoms

If the check engine light or service engine soon stay on, your BMW may drive fine if the trigger is due to EVAP related fault code. Unless the problem is more serious in which case you may notice performance issues such as: 

  • BMW engine misfire
  • BMW won't accelerate
  • Stuck in limp mode
  • Engine shakes at idle
  • BMW engine overheats
  • Poor acceleration
  • Erratic idle
  • Hard to start

BMW Service Engine Soon light may be on without any noticeable performance issues.

Back to top

8. Common Causes of Check Engine Light

There are hundreds of problems that may trigger the check engine or service engine soon in a BMW. BMW specific problems include:

  • VANOS,
  • cracked or loose hoses,
  • old battery,
  • bad mass air flow sensor,
  • low fuel level,
  • bad charcoal carbon canister,
  • wire harness,
  • High-Pressure Fuel Pump (HPFP) failure,
  • crankshaft sensor bad
  • injectors (when applicable).

Do not start replacing BMW parts without at a reading the fault codes. If you don't have a BMW scan tool, have a shop that specializes in BMWs read the codes and troubleshoot the problem for you. Once you have a diagnosis performed, you can decide if the repair is something that you can tackle yourself or let a BMW shop complete the work. 


Back to top

Check Engine Light Flashing

If your check engine light is flashing it means that the engine control unit has detected a misfire. You should stop as soon as possible and have your vehicle towed if necessary to prevent further damage to the engine or catalytic converter. 

What this means is that one or more of your cylinders are not working properly. This can be caused by a number of things such as bad spark plug, faulty ignition coil, bad ECU, clogged catalytic converter. 

If your car is flashing the check engine light and you continue to drive, you can damage the engine or the catalytic which can cost anywhere from $800 to $1500 to replace.

Top 10 Causes of Check Engine Light

Here is a list of the most common causes of Check Engine Light. Average costs to repair these problem has been included. Please note that for high-end vehicles the repair cost can be outside of this range. The repair costs shown below are typical prices you will pay at the dealers and auto repair shop. When a DIYer performs these repairs the average cost is significantly lower. 

  1. Oxygen Sensors 
    • Repair Cost: $200-$400
    • Repair Difficulty: Easy 
  2. Catalytic converter
    • Repair Cost: $750-$1500
    • Repair Difficulty: Moderate 
  3. Spark Plugs
    • Repair Cost: $250-$600
    • Repair Difficulty: Easy
  4. Loose Gas Cap
    • Repair Cost: Free - $25
    • Repair Difficulty: Very Easy
  5. Mass Air Flow MAF Sensor
    • Repair Cost: $200-$400
    • Repair Difficulty: Easy
  6. EVAP Purge Control Valve
    • Repair Cost: $120-$400
    • Repair Difficulty: Easy
  7. Ignition Coils
    • Repair Cost: $140-$600
    • Repair Difficulty: Easy
  8. Thermostat
    • Repair Cost: $200-$650
    • Repair Difficulty: Moderate
  9. Camshaft Position Sensor
    • Repair Cost: $150-$400
    • Repair Difficulty: Easy
  10. Fuel Injectors
    • Repair Cost: $350-$650
    • Repair Difficulty: Easy

Important Notes

  1. Clearing the check engine light using a scanner or by disconnecting the car battery does not fix the problem itself. Clearing codes without fixing the problem simply erases the codes from Engine Control Unit memory. Also keep in mind that if your car requires an emissions test soon after you clear the code, you will fail the emissions test. Clearing (CEL) codes also set the emissions readiness indicators to NOT READY. The car will require a few days of driving or a specific drive cycle to test all the emission systems and set them to READY.
  2. We recommend that you get a second opinion from a professional before you replace any parts. Do not replace car parts based on the fault code alone. It is important to consider the symptoms and the code before you come to a conclusion. For example, you may get a code for a bad oxygen sensor. While the oxygen sensor can surely be defective, a code for oxygen sensor can also be triggered by a cut wire, bad connector,  bad catalytic converter etc. Keep in mind that even a mechanic may have a difficult time diagnosing those rare cases. 
  3. If your check engine light turns on while driving continually monitor the engine temperature and oil pressure light. If any of these lights turn on, safely pull over and turn off the engine. 
  4. Do not ignore the Check Engine Light warning. Diagnose your vehicle as soon as possible.
  5. Auto parts stores such as Advance Auto Parts or AutoZone may offer free scanning of the Check Engine Light. 
  6. Check Engine Light (CEL) may also be referred to as Service Engine Soon (SES), malfunction indicator lamp (MIL). 

Frequently Asked Questions

Yes, disconnecting the battery usually clear the ECU codes. By turning the check engine light off this way you will not fix the problem. If you believe the check engine light needs to be off, drive the car for a few days and the CEL will reset itself. The Onboard Diagnostic System in your car continually monitors your vehicle and will turn off the CEL if the problem is solved. If the problem hasn't been resolved, even if you disconnect the battery, the CEL will come back up again which can be as soon as you restart the car or up to a few days.

If check engine light is on, it will not pass emission inspection/smog test. If the light was recently reset with an OBD2 scanner or by disconnecting the battery, you need to drive the car for a couple of days for the systems to be ready for testing.

It could be because you are using an OBD2 scanner that does not support the protocol used in your car. Try a different scanner. Also, there may be an issue communicating with the ECU due to a damaged wire or ECU malfunction.

No. The check engine light is not the reason why the car doesn't start. If the car doesn't start, read the codes and maybe the CEL will give you a code that can help you diagnose the car. Clearing codes will not make your car start.

It may be just bad timing. An oil change is not going to trigger the CEL. Unless MAYBE a sensor got accidentally unplugged, disconnected or damaged during the oil change. Take your car back to the auto repair shop that changed your oil and have them diagnose the problem.

No, the CEL should not turn on after routine maintenance. If you modified your engine, transmission, exhaust, intake, fuel system or other systems it can affect engine and emission control system, causing check engine or service engine soon light to come on. CEL should not come on if you changed tires or tire size.

Drive the car for a couple of days and allow the ECU to reset itself. If the CEL still remains on, read codes.

The check engine light is trying to tell you that there is a problem with your engine. It could be low coolant, stuck thermostat, transmission not shifting. Figure out why your car is overheating first and address that problem. DO NOT CONTINUE TO DRIVE IF YOUR CAR OVERHEATS.