O2 Sensor Negative Voltage Bank 1 Sensor 2
The P2A07 code indicates that the oxygen sensor (O2S) in Bank 1, Sensor 2 (downstream of the catalytic converter) is reporting a negative voltage, which is abnormal. Normally, O2 sensors generate a voltage between 0.1 and 0.9 volts. A negative voltage suggests a wiring issue, such as a short to ground, a faulty sensor, or a problem with the engine control module (ECM). This can cause incorrect air-fuel ratio adjustments and affect emissions.
01. Most Common Causes
- Faulty oxygen sensor
- Wiring or connector damage (short to ground or open circuit)
- Corroded or loose electrical connections
- ECM malfunction
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy
- Failed emissions test
- Rough idle or hesitation
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for other related codes.
Step 2: Visually inspect the O2 sensor wiring and connector for damage, corrosion, or loose connections.
Step 3: Measure the sensor's voltage output with a multimeter while the engine is running; compare to specifications.
Step 4: If wiring is intact, replace the O2 sensor (Bank 1, Sensor 2).
Step 5: Clear the code and test drive to see if the code returns.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe to drive short distances, but the vehicle may fail an emissions test and fuel economy may suffer. Prolonged driving could damage the catalytic converter.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a DIY replacement of the sensor, or $100 to $300 if done by a shop, including parts and labor.