P1191 (Volkswagen, Audi, Skoda, Seat) Linear lambda probes in front of the catalyst are mixed up
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P1191 – OBD-II Trouble Code Technical Description
Fault code P1191 indicates that the linear oxygen sensors in front of the catalyst are reversed (switched places) in Volkswagen, Audi, Skoda, Seat cars.
What does the fault code mean P1191?
Trouble code P1191 indicates an error in the location of the linear oxygen sensors in front of the catalyst in Volkswagen, Audi, Skoda and Seat vehicles. Trouble P1191 occurs when the oxygen sensors upstream of the catalytic converter are reversed. This can happen, for example, if the sensors are incorrectly installed or replaced, when the mechanic mistakenly mixed them up. It is important to note that the correct location of the oxygen sensors is important for the proper operation of the engine management system and catalytic converter. Confused sensors can lead to incorrect analysis of the exhaust gas composition and, as a result, to improper engine operation and increased emissions of harmful substances.
Possible reasons
Several possible reasons for the P1191 error:
- Incorrect installation or replacement of oxygen sensors: The error may occur if the oxygen sensors were incorrectly installed or replaced and the mechanic misplaced them.
- Faulty wiring or connectors: Problems with wiring or connections can cause the oxygen sensors to not be connected correctly, which can also cause P1191.
- Incorrect labeling or identification of sensors: Oxygen sensors can sometimes be incorrectly labeled or identified, which can cause them to be installed incorrectly.
- Problems with oxygen sensors or catalyst: In rare cases, the P1191 code can be caused by the oxygen or catalytic converter sensors themselves if they are not functioning correctly or have other problems.
- Software or hardware problems in the engine management system: Certain technical problems in the engine control module (ECU) or other control system components can cause P1191.
It is important to note that additional diagnostics using specialized equipment and the knowledge of an auto mechanic may be required to accurately determine the cause of the P1191 code.
What are the symptoms of a fault code? P1191?
Symptoms for code P1191 may include the following:
- check engine: One of the most common symptoms is the activation of the “Check Engine” light on your car’s dashboard. This may be the first sign of trouble.
- Unstable engine performance: Incorrectly positioned oxygen sensors can cause engine instability, which may manifest as shaking, rough running, or rough idling.
- Loss of power or deterioration in performance: Improper operation of the control system due to P1191 may result in loss of power or poor overall engine performance.
- Increased fuel consumption: Improper placement of oxygen sensors can result in an incorrect fuel/air mixture, which can result in increased fuel consumption.
- Unusual sounds or vibrations: Problems with the engine management system may result in unusual sounds or vibrations while driving.
- Increased emissions of harmful substances: Improper placement of oxygen sensors can result in increased emissions of harmful substances in the exhaust gases, which may be noticeable during inspection or stationary tests.
These symptoms may occur to varying degrees depending on the specific problem and the condition of the vehicle. If you experience any of these symptoms, it is recommended that you contact a qualified technician for diagnosis and repair.
How to diagnose a fault code P1191?
Diagnosis for DTC P1191 may include the following steps:
- Reading the error code: Using a diagnostic scan tool, you must read the P1191 fault code from the engine control module (ECU) memory.
- Checking the correct placement of oxygen sensors: Check whether the oxygen sensors in front of the catalytic converter are installed correctly. Make sure that the sensor in bank 1 (usually closer to the engine) is actually installed in bank 1, and the sensor in bank 2 (usually further from the engine) is actually installed in bank 2.
- Checking wiring and connections: Inspect the wiring and connectors associated with the oxygen sensors. Check them for damage, corrosion or breaks. Make sure the connections are secure.
- Checking the performance of oxygen sensors: Test the performance of the oxygen sensors using a multimeter or specialized equipment. Make sure that both sensors respond correctly to changes in oxygen content in the exhaust gases.
- Checking other engine management system components: Perform additional tests and diagnostics on other engine management system components such as the mass air flow (MAF) sensor, coolant temperature sensor, and others. Incorrect operation of these components can also lead to P1191.
- Clearing the error code: After diagnosing and repairing faults, it is necessary to clear the error code P1191 from the memory of the engine control module using a diagnostic scanner.
If after following these steps the problem does not resolve, it is recommended that you contact a professional auto mechanic or auto repair shop for more detailed diagnosis and repair.
Diagnostic errors
When diagnosing DTC P1191, the following errors may occur:
- Incorrect interpretation of error code: Misunderstanding the meaning of error code P1191 can lead to incorrect conclusions about the cause of the problem. For example, a mechanic may believe that the problem is related to the oxygen sensors, when in fact it may be caused by improper installation or wiring of the sensors.
- Incomplete check of oxygen sensors: A mechanic may limit himself to checking only the oxygen sensors themselves, without paying attention to their location or the condition of the wiring. This may result in missing the cause of the error.
- Skip checking other system components: Some mechanics may not check other engine management system components that may affect the performance of the oxygen sensors, such as the mass air flow sensor or coolant temperature sensor.
- Wrong solution to the problem: In case of misdiagnosis, the mechanic may take the wrong steps to correct the problem, such as replacing the oxygen sensors, when in fact the problem is due to their incorrect location.
- Insufficient error code removal: After a repair, the mechanic may forget or skip the step of clearing the P1191 fault code from the engine control module's memory, which may cause the error to persist even after the problem is resolved.
It is important to carry out diagnostics with due attention to each step and consider all possible causes of the problem in order to avoid errors and ensure effective troubleshooting.
How serious is the fault code? P1191?
Trouble code P1191 is not typically a critical or emergency trouble code, but does indicate potential problems with the engine management system that could cause engine malfunction and poor vehicle performance. Although the P1191 error is not extremely serious, its presence can lead to a number of undesirable consequences:
- Performance degradation: Incorrect operation of oxygen sensors can lead to unstable engine operation and loss of power. This can affect the vehicle's overall performance and driving comfort.
- Increased emissions of harmful substances: Improper fuel/air mixture due to P1191 can result in increased exhaust emissions. This may attract the attention of inspectors during technical inspections or lead to unsatisfactory results in compliance tests.
- Increased fuel consumption: Improper operation of the engine management system can result in increased fuel consumption due to an inefficient fuel/air mixture. This may negatively affect the economic efficiency of using the vehicle.
Although the P1191 code does not require immediate technical attention, it is recommended that you have a qualified technician diagnose and repair it to avoid deterioration of your vehicle and maintain optimal performance.
What repair will help eliminate the code? P1191?
Resolving trouble code P1191 depends on the specific cause of the error, several possible repair actions:
- Checking and correcting the location of oxygen sensors: If the oxygen sensors are not installed correctly, they should be properly relocated according to the vehicle manufacturer's recommendations. This may require removing and reinstalling the sensors.
- Checking and replacing wiring and connections: Check the wiring and connectors associated with the oxygen sensors. Replace damaged or broken wires and ensure connections are secure.
- Checking and replacing oxygen sensors: If the oxygen sensors are faulty or do not function correctly, they should be replaced with new sensors that meet the manufacturer's specifications.
- Checking and correcting the reference voltage: Check the reference voltage supplied to the oxygen sensors. Make sure the voltage meets the manufacturer's specifications. Adjust the reference voltage if necessary.
- Additional diagnostics and repairs: If the problem is not resolved after performing the above measures, a more in-depth diagnosis of other components of the engine management system may be required. For example, check the mass air flow (MAF) sensor, ignition system, or intake manifold for problems.
After repair work is completed, it is necessary to clear error code P1191 from the memory of the engine control module using a diagnostic scanner. If you do not have experience in automotive repair, it is recommended that you contact a professional auto mechanic or auto repair shop to perform diagnostics and repairs.
