What Does P2243 Mean?
The PCM detected an open circuit or complete loss of the reference voltage circuit for Bank 1 Sensor 1 oxygen sensor. This prevents the sensor from generating proper voltage signals for fuel mixture control.
Common Causes
35%
Broken or disconnected wiring in O2 sensor reference voltage circuit
30%
Corroded or damaged O2 sensor connector terminals
20%
Failed oxygen sensor with internal circuit failure
10%
PCM internal reference voltage circuit failure
5%
Damaged O2 sensor due to contamination or physical damage
Diagnostic Steps
1
Step 1: Inspect Bank 1 Sensor 1 O2 sensor connector for damage, corrosion, or backed-out pins
2
Step 2: Check continuity of reference voltage wire from sensor connector to PCM connector
3
Step 3: Measure reference voltage at O2 sensor connector with sensor connected (typically 0.4-0.5V with engine off)
4
Step 4: Backprobe signal wire and observe voltage during engine operation (should fluctuate 0.1-0.9V)
5
Step 5: If no reference voltage present at connector, check PCM connector and internal PCM fault
Estimated Repair Cost
$150 - $500
Parts + labor, varies by vehicle and location
The PCM detected an open circuit or complete loss of the reference voltage circuit for Bank 1 Sensor 1 oxygen sensor. This prevents the sensor from generating proper voltage signals for fuel mixture control.
The most common cause of P2243 (O2 Sensor Reference Voltage Circuit/Open Bank 1 Sensor 1) is: Broken or disconnected wiring in O2 sensor reference voltage circuit
Typical repair costs for P2243 range from $150 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive but engine will run in open-loop mode, causing poor fuel economy, rough running, and increased emissions. Should be repaired promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2243 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System / Emissions Control
Difficulty
Type
Generic (SAE)
Recommended Tools
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