How serious is a P2249 code?
Insufficient voltage in the oxygen sensor (O2) reference circuit can lead to decreased fuel efficiency and reduced engine performance. A P2249 code is considered serious and should be addressed promptly to avoid more significant consequences.
What are the symptoms associated with code P2249?
Symptoms of a P2249 fault code may include:
- Reduced fuel efficiency
- Decreased engine performance
- Error codes related to misfires or lean/rich mixtures
- Illumination of the “Service Engine Soon” light
What are the common causes of this code?
The main causes of code P2249 include:
- Blown O2 sensor fuse
- Oxygen sensor failure
- Damaged, worn, cut, or disconnected wiring and/or connectors
How to diagnose a P2249 code?
To diagnose a P2249 code, you will need a diagnostic scanner, a digital voltmeter/ohmmeter (DVOM), and a reliable source of information about your vehicle. You can also search for technical service bulletins (TSBs) related to this code, which can save time and provide a quick solution.
- Connect the scanner to the vehicle’s diagnostic port and retrieve all stored error codes along with freeze frame data.
- Clear the codes and test the vehicle. If the code returns or the PCM (engine control unit) enters “preparation” mode, it may indicate that the code is intermittent. In this case, the condition causing the code needs to worsen for more accurate diagnosis.
- Perform a visual inspection of the wiring and connectors. Replace any damaged wiring.
- Test the O2 sensor voltage with the DVOM. If no voltage is detected, check the fuses. Replace any faulty fuses if necessary.
- Test the corresponding PCM circuit. If voltage is not present, it may indicate a connection issue between the sensor and the PCM. If voltage is present but incorrect, the PCM may be faulty or improperly programmed.
Testing oxygen sensors
To test O2 sensors:
- Start the engine and let it reach its normal operating temperature.
- Monitor the O2 sensor data using the connected scanner. Pre-catalytic converter oxygen sensors should show continuous voltage fluctuation between 1 and 900 millivolts, while post-catalytic converter sensors will stabilize at a relatively constant value. If the sensors do not respond as expected, they are likely faulty.
A blown O2 sensor fuse may not be the cause of the P2249 code, but rather a response to a short circuit in the sensor circuit