What Does P2249 Mean?
The oxygen sensor reference voltage for Bank 2 Sensor 1 is reading lower than the minimum acceptable threshold. This indicates a voltage drop or short to ground in the reference circuit.
Common Causes
40%
Reference voltage wire shorted to ground or signal ground
25%
Failed oxygen sensor with internal short to ground
20%
Damaged or pinched wiring near exhaust components
10%
Corroded connector causing voltage drop and moisture intrusion
5%
ECM internal short in reference voltage circuit
Diagnostic Steps
1
Step 1: Disconnect Bank 2 Sensor 1 and measure reference voltage at ECM side of connector (should be 0.4-0.5V)
2
Step 2: Check for short to ground on reference voltage wire using ohmmeter with sensor disconnected
3
Step 3: Inspect wiring harness routing near exhaust manifold and heat shields for damage or chafing
4
Step 4: If wiring tests good, connect known-good O2 sensor and verify reference voltage returns to normal
5
Step 5: Check ECM connector pins for corrosion or bent terminals if sensor and wiring are confirmed good
Estimated Repair Cost
$120 - $600
Parts + labor, varies by vehicle and location
The oxygen sensor reference voltage for Bank 2 Sensor 1 is reading lower than the minimum acceptable threshold. This indicates a voltage drop or short to ground in the reference circuit.
The most common cause of P2249 (O2 Sensor Reference Voltage Circuit Low Bank 2 Sensor 1) is: Reference voltage wire shorted to ground or signal ground
Typical repair costs for P2249 range from $120 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive but vehicle will run in open-loop mode affecting fuel economy and emissions. Prolonged operation may damage catalytic converter.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2249 to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
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