P1138 (Volkswagen, Audi, Skoda, Seat) Long-term fuel control system, idle, bank 2, mixture too lean
Content
P1138 – OBD-II Trouble Code Technical Description
Trouble code P1138 indicates that the air/fuel mixture is too lean (at idle) in engine block 2 in Volkswagen, Audi, Skoda, Seat vehicles.
What does the fault code mean P1138?
Trouble code P1138 indicates the engine bank 2 air/fuel mixture is too lean at engine bank 2 idle. This means that the fuel/air mixture (at idle) in block 2 of the engine contains too little fuel and too much air, which can cause performance problems.
Possible reasons
Possible causes of DTC P1138:
- Problems with the fuel system, such as a clogged or faulty fuel filter, insufficient fuel pressure, or defects in the fuel injection system.
- The mass air flow (MAF) sensor, which measures the amount of air entering the engine and transmits this information to the engine management system, is not functioning properly.
- Problems with the oxygen (O2) sensor, which monitors the oxygen content of exhaust gases and helps regulate the fuel-air mixture.
- An air leak in the intake system or intake manifold, which can result in insufficient air pressure and, as a result, air mixing with fuel in inadequate proportions.
- Ignition system malfunction, such as problems with the ignition coils, spark plugs, or wires.
- Problems with the ECU (electronic control unit), which may be faulty or have software problems.
- The presence of other malfunctions in the engine management systems, such as coolant temperature sensors or pressure sensors in the intake manifold.
What are the symptoms of a fault code? P1138?
Symptoms for DTC P1138 may include:
- Loss of power: It is possible that the engine will experience a loss of power due to insufficient fuel in the mixture.
- Unstable idle: Rough idle may occur when the fuel/air mixture is not optimal.
- Increased fuel consumption: Because the mixture is too lean, the engine may consume more fuel to maintain normal operation.
- Engine slowdown or intermittent operation: In some cases, engine sluggishness or rough running may occur due to improper fuel/air mixture.
How to diagnose a fault code P1138?
To diagnose DTC P1138, you can follow these steps:
- Checking the oxygen sensor (Oxygen Sensor): Check the condition and operation of the oxygen sensor. It must transmit the correct signals to the engine control module (ECU).
- Checking the fuel injection system: Check the condition of the injectors and their operation. Make sure they are working correctly and delivering the correct amount of fuel.
- Checking the air supply system: Check the condition of the air filter and the operation of the mass air flow (MAF) sensor. Make sure the air supply system is not clogged or clogged.
- Checking for air leaks: Check the system for air leaks such as cracks or damage in the air manifold or air hoses.
- Fuel pressure check: Check the fuel pressure in the system. Low fuel pressure can cause the mixture to become too lean.
- Checking the condition of the catalyst: Check the condition of the catalytic converter for blockages or damage that could affect the performance of the exhaust aftertreatment system.
These steps will help identify possible causes of the source of the problem associated with DTC P1138. If you are not confident in your skills, it is better to contact a specialist.
Diagnostic errors
Errors in diagnosing the P1138 trouble code can be caused by several factors, some common errors are:
- Insufficient fuel system diagnostics: The error may occur if the entire fuel system, including fuel pressure, fuel injector operation and fuel pressure regulator operation, are not sufficiently diagnosed. Failure to pay enough attention to these aspects may result in missing the root cause of the problem.
- Ignoring other sensors and components: Код P1138может быть связан с неисправностью датчика кислорода (O2 sensor), но также может иметь отношение к другим компонентам системы впрыска топлива, например, массовому расходу воздуха (MAF sensor), датчику температуры воздуха, регулятору давления топлива и другим.
- Incorrect interpretation of scan data: Interpretation of scan data may be incorrect due to lack of experience or understanding of the system. This can lead to erroneous conclusions about the state of the system and incorrect actions to repair it.
- Use of low-quality components: When replacing components such as the oxygen sensor, using low-quality or non-original parts may cause problems or continuation of the problem.
- Ignoring other symptoms: Some car enthusiasts may focus solely on the P1138 code while ignoring other symptoms such as rough running, loss of power, or poor fuel economy. This can make it difficult to identify and fix all problems.
To avoid these errors, it is important to conduct a comprehensive diagnosis of the entire system, pay attention to all symptoms and use quality components when replacing parts.
How serious is the fault code? P1138?
Trouble code P1138 indicates that the air/fuel mixture is too lean at idle speed. Depending on the specific circumstances and underlying issues, the severity of this code may vary.
If the problem persists, it may result in the following:
- Loss of power: A lean air/fuel mixture can result in insufficient engine power, affecting the overall performance of the vehicle.
- Increased fuel consumption: When the mixture is lean, the engine may require more fuel to operate properly, resulting in increased fuel consumption.
- Engine damage: If the vehicle is driven continuously with a lean mixture, the engine may overheat and damage valves or other important components.
- Ecological problems: A lean mixture can lead to an increased release of harmful substances into the environment, which has a negative impact on the environment.
So, although the P1138 code is not a critical flash failure, it still requires careful attention and repair to avoid serious consequences to engine performance and vehicle performance.
What repair will help eliminate the code? P1138?
To resolve DTC P1138, follow these steps:
- Checking the fuel supply system: Check the condition of the fuel injectors, fuel pump and fuel filter. Make sure the fuel system is maintaining the correct fuel pressure and delivering enough fuel to the injectors.
- Checking sensors: Check the condition of the mass air flow (MAF) sensor and oxygen sensor (O2). They may be dirty or damaged, preventing them from functioning properly.
- Checking for Vacuum Leaks: Leaks in the vacuum system can cause air and fuel to mix in inappropriate proportions. Check all vacuum hoses for leaks.
- Replacing the oxygen sensor: If the oxygen sensor gives incorrect signals or is faulty, it should be replaced.
- Software update: Sometimes updating the engine software can help fix the lean problem.
- Checking the air filter: A clogged air filter can prevent proper air flow, which can lead to a lean air-fuel mixture.
Once the problem has been identified and corrected, it is recommended to reset the DTC using a diagnostic scan tool. If the problem persists or further assistance is needed, it is recommended that you contact a professional auto mechanic or service center.
