The P2249: O2 Sensor Reference Voltage Circuit Low Bank 2 Sensor 1 code refers to a condition where the oxygen (O2) sensor reference voltage for Bank 2 Sensor 1 is lower than expected. This low voltage issue can prevent the sensor from functioning correctly, resulting in incorrect air-fuel ratio adjustments. The potential causes include a faulty O2 sensor, wiring issues, or connector problems that need to be addressed to ensure proper sensor function.
P2249 – Quick Overview
| Code | Information |
|---|---|
| Meaning | P2249: O2 Sensor Reference Voltage Circuit Low Bank 2 Sensor 1 |
| Is it serious? | Yes, as low reference voltage can lead to incorrect sensor readings, affecting the air-fuel mixture, reducing fuel efficiency, and increasing emissions. |
| Possible causes | – Low voltage in O2 sensor reference voltage circuit for Bank 2 Sensor 1 – Faulty O2 sensor – Wiring issues – Connector problems |
| How to diagnose? | – Measure voltage in the O2 sensor reference voltage circuit for Bank 2 Sensor 1 – Test the sensor for proper operation – Inspect wiring and connectors for faults |
P2249 Meaning
The P2249: O2 Sensor Reference Voltage Circuit Low Bank 2 Sensor 1 code indicates that the reference voltage supplied to the O2 sensor for Bank 2 Sensor 1 is below the specified range. The reference voltage is crucial for the proper operation of the sensor, which monitors oxygen levels in the exhaust. If the voltage is too low, the sensor cannot accurately relay data to the engine control unit, resulting in incorrect adjustments of the air-fuel ratio, which can affect engine performance and emissions.
Step-by-step diagnostic guide
| Action | Description | Tools Needed |
|---|---|---|
| Check for Other Codes | Use an OBD-II scanner to determine if there are other related codes. These can provide additional context to determine if the issue is isolated or part of a larger fault. | OBD-II Scanner |
| Measure Voltage in the O2 Sensor Reference Voltage Circuit | Use a multimeter to measure the voltage in the reference voltage circuit for Bank 2 Sensor 1. Compare the measured voltage with the manufacturer’s specifications. A lower-than-expected voltage could indicate an issue with the power supply, wiring, or sensor itself. | Multimeter, Vehicle Service Manual |
| Test the Sensor for Proper Operation | Use a diagnostic tool to test the operation of the O2 sensor. The test should verify that the sensor is receiving the correct reference voltage and providing proper readings. If the sensor fails this test, it may need to be replaced. | Diagnostic Scanner, Multimeter |
| Inspect Wiring and Connectors for Faults | Visually inspect the wiring and connectors related to Bank 2 Sensor 1. Look for any signs of frayed or broken wires, loose connections, or corrosion on the connectors that might be causing a drop in voltage. Repair or replace any damaged components. | Flashlight, Safety Gloves |
| Check the Sensor Connector Condition | Carefully examine the sensor connector to ensure that there are no bent pins, poor contacts, or signs of corrosion. Poor connectivity can result in low voltage reaching the sensor. Ensure the connector is firmly attached and properly aligned. | Flashlight |
| Clear the Code and Test Drive | After performing the necessary repairs, use an OBD-II scanner to clear the fault code. Conduct a test drive to monitor the sensor’s performance and verify that the reference voltage has returned to normal, confirming that the problem is resolved. | OBD-II Scanner, Vehicle Owner’s Manual |
| Recheck for Codes | After the test drive, re-scan the vehicle to ensure that the P2249 code has not returned. If the code persists, further diagnostic procedures will be required to identify any unresolved issues. | OBD-II Scanner |
Free PDF: How to choose OBD2 scanner
I’ve made you a free PDF to choose the OBD2 scanner in 5 minutes.
✅ Which OBD2 scanner is best?
✅ Which type should you get (DIY, Pro, Hobby)
✅ What is the best scanner for the exact brand/feature (e.g best for BMW)
✅ How to get a Bi-Directional tool for as cheap as $40
✅ Discount coupons for scanners
PDF is 100% free and it is designed to help you pick a scanner in less than a few minutes! Not a boring 50-page guide.
Just tell me where to send it.
Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)