O2 Sensor Reference Voltage Circuit Low (Bank 1 Sensor 1)
The P2248 code means the vehicle's onboard diagnostic system has detected: O2 Sensor Reference Voltage Circuit Low (Bank 1 Sensor 1). This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $100 - $400 (parts and labor)
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Common Symptoms
- Check Engine Light on
- Engine runs poorly
- Rich or lean condition
- Failed emissions test
- Rough idle
Probable Causes (Ranked by Likelihood)
- Failed O2 sensor heater or internal reference Very High
- Wiring fault in O2 sensor reference circuit High
- ECM O2 reference output circuit fault Moderate
- Corroded O2 sensor connector affecting reference Low
Step-by-Step Diagnostic Procedure
-
Measure O2 sensor reference voltage at the sensor connector
-
Check ECM reference output at the ECM connector
-
Inspect wiring between ECM and O2 sensor for damage
-
Replace O2 sensor if reference circuit within sensor is faulty
Frequently Asked Questions
What is the O2 sensor reference voltage?
The ECM provides a reference voltage (typically 2.5V or 3.3V) to the wideband O2 sensor to establish a baseline for measuring oxygen content in the exhaust.
Can a bad ECM cause this code?
It is possible but rare. The vast majority of these codes are caused by a failed O2 sensor or wiring issue. Test the sensor and wiring thoroughly before considering ECM replacement.
Do I need a special tool to test this?
A multimeter can measure reference voltage and resistance. A scan tool with live data capability is also very helpful for monitoring O2 sensor operation in real time.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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