BMW fault codes: Common issues & troubleshooting

BMW fault codes: Common issues & troubleshooting
You can get a lot of information about your car with an OBD2 reader. Even the most basic tools will provide you with various fault codes, which are short-hand for various issues. Unfortunately, sometimes that’s all you get – fault codes without much further explanation.

Car manufacturers also have their own unique fault codes, which can be read with specific OBD scanners. BMW fault codes are no different – they’re manufacturer-specific trouble codes that tell you something needs attention.
Some issues, indicated by BMW fault codes, are benign and won’t cause major issues quickly, or they can be resolved with minor repairs. Others, however, may require immediate attention to avoid major faults.

 How to read BMW fault codes

To get access to any fault codes, you’ll need an OBD2 reader. While all OBD-readers will give you generic fault codes, you should also check if the diagnostic tool is tailored for BMWs. Manufacturer-specific fault codes are often much more precise and specific, which will make diagnostics easier.
Once you have an OBD2 reader, follow these steps: 
  1. Find the   OBD2  port. Usually, you’ll find it under the dashboard, near the driver’s seat. There are other locations, however, such as under the glove compartment or between the transmission and cup holder. 
  2. Plug in the OBD2 reader.  You’ll need to simply connect the plug to the port.
  3. Turn on the ignition. You don’t need to start the engine itself. 
  4. Scan the codes. Follow the instructions on your OBD2 reader to start looking for fault codes.
  5. Interpret the codes. Advanced OBD scanners will give you more than just the fault codes. Usually, they will include some additional information. If y our OBD2 reader doesn’t give other information, use guides to find out what they mean. In either case, make sure your OBD2 reader can read BMW fault codes specifically to get more information about the issue.

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Common BMW fault codes

BMW fault code: P0300 – Random/multiple cylinder misfire detected
One or several of your BMW’s cylinders (usually between 4 and 6) are misfiring. There can be several different causes, most of them related to other internal parts: spark plugs could be worn out, the fuel injector could be clogged, or the ignition coil could need to be replaced. 
It’s usually best to check for additional BMW fault codes to diagnose the real problem. Some of these parts can be replaced relatively easily. However, so if you have experience with repairs, you can fix it yourself.

BMW fault code: P1014 – Valvetronic reference eccentric shaft sensor parity error
The valvetronic system adjusts valve intake and duration, helping with fuel economy and reducing emissions. Various parts of the valvetronic system could be faulty, such as the shaft sensor being shorted or experiencing poor electrical connection. Additionally, the "Check Engine" light will likely be turned on if the system is experiencing issues.
As the system is highly complicated and involves many electrical parts, it’s highly recommended to get a professional BMW mechanic to engage with repairs. It’s best to do that as soon as possible, as P1014 indicates a major issue.
BMW fault code: P0171, P0174 – System too lean
This fault code indicates that the air-fuel mixture ratio is unusual, leaning towards too much air or too little fuel. Numerous components could be at fault, ranging from failure to close the fuel tank cap to a faulty oxygen sensor. Looking for more fault codes to diagnose the exact issue should be considered.
A system that runs too lean can cause various issues, such as rough idling. In extreme cases, it may cause damage to internal components, so the issue should be addressed as soon as possible.
BMW fault code: P0420 – Catalyst system efficiency below threshold (bank 1)
Indicates that the catalytic converter isn’t performing as expected. Issues could be related to your BMW’s exhaust or fuel systems, making it tricky to diagnose perfectly. The "Check Engine" light will also turn on if P0420 is displayed.
You should consult with a qualified BMW mechanic for repairs. Continuing to drive the car will not only lead to degraded performance but will potentially further damage the catalytic converter, which is an expensive part to replace.

BMW fault code: P112F – Air mass system
A faulty air mass system will cause issues for the engine control module to calculate the correct amount of fuel to inject for proper combustion. Air mass system issues can be caused by a variety of factors, such as a faulty Mass Air Flow (MAF) sensor, air leaks in the intake system, or electrical issues related to the mass air flow sensor.
P112F could indicate both minor and major issues. If the MAF is dirty, it’ll continue to function properly once cleaned and is unlikely to cause damage if unattended. If it has completely failed or there’s a major air leak, there may be significant performance degradation, poor fuel economy, and could cause damage to internal components over the long run.

BMW fault code: P1632 – Throttle valve adaptation conditions not met
This BMW fault code indicates that the throttle valve adaptation attempted by the engine control module failed, and proper air intake couldn’t be ensured. Issues may be caused by a faulty throttle body, worn out throttle position sensor, wiring issues, and many other things.
Issues with the throttle valve can cause the vehicle to enter limp mode. In general, regardless of the true underlying cause (i.e., whether it’s the throttle body or anything else), P1632 should be addressed by a professional as soon as possible.
BMW fault code: P1176 – Heated catalyst power switch overtemperature condition bank 1
The power switches, connected to the catalytic converter, support the heating element, raising the temperature and allowing the vehicle to reduce emissions. This fault code indicates that the power switch in Bank 1 has exceeded safe operating limits.
Most of the time, the issue will be related to the power switch itself or, potentially, with wiring. Since it’s a highly specific BMW fault code, it’s recommended to send your vehicle to a professional for repairs.
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BMW fault code: P1449 – DMTL, system fault: Pump current too high during reference measurement 
This fault code appears when the Diagnostic Module Tank Leakage (DMTL) system, which helps check for fuel leaks, uses more than 40 mA of current during a test. This usually means there's something wrong with the leak diagnostic pump or related electrical components. 
First, to troubleshoot this problem, clear all fault codes related to the DMTL system. Then, start the vehicle again. If the P1449 code doesn't reappear, no further actions are needed. However, if it shows again, replace the DMTL pump to prevent Evaporative Emission Control (EVAP) problems. 
BMW fault code: P1290 – Electric wastegate, adaptation: Cold start not learned 
This fault code pops up when there’s a problem with the electric wastegate valve during the catalytic converter's heating phase. It occurs when the valve doesn’t reach its required position, thus affecting the control of exhaust gases needed to heat the converter. 
To resolve this issue, examine the wastegate's linkage for any damage or signs of wear. If the problem persists, you may need to replace either the electrical controller drive or the wastegate valve. 
BMW fault code: P1447 – DMTL, system fault: pump current reaches limit value during valve test 
This fault code is triggered when there's an issue with the DMTL system during a solenoid valve test. The problem occurs when the power consumption of the pump changes by less than 2 mA, which is not typical and indicates that the DMTL solenoid valve may be faulty. 
To troubleshoot this problem, first clear all fault codes associated with the DMTL system and then start the vehicle. If the P1447 code doesn't reappear, no further actions are needed. However, if the fault reoccurs, you may need to replace the DMTL unit. 
BMW fault code: P1030, P1017 – Valvetronic system: No adjustment possible 
The Valvetronic system is responsible for timing the engine valves for better fuel economy and performance. This code appears when the system can't adjust the engine valves as needed. 
To fix the problem, first clear the fault codes with an OBD scanner. If the problem returns, check the wiring between the Valvetronic motor and the engine control unit and ensure the system's power is stable. If these checks don't resolve the problem, you may need to replace the servomotor or eccentric shaft. 
BMW fault code: P0456 – EVAP emission control system leak detected 
This fault code means there's a small leak in the EVAP system that controls your car's fuel vapors. 
To fix the issue, check if the fuel cap is tight and inspect its rubber seal for any damage. Make sure the tank vent valve and connections are properly installed. If the problem persists, check the entire system for leaks, including the fuel tank and pipes. Replace any damaged parts, such as the tank vent valve or diagnostic module, if the leak continues.