A short to ground or chafed wire in the sensor reference voltage circuit; Corroded or loose electrical connector at the oxygen sensor or engine computer; Failed oxygen sensor with an internal short in the reference circuit; Open or high-resistance ground connection for the sensor heater or signal return; Faulty engine computer driver for the reference voltage circuit, though uncommon; Contamination or damage to the sensor wiring from heat or debris

DTC codes / P22xx · Fuel and air metering (injector circuits) / P2245

P2245O2 Sensor Reference Voltage Circuit Low (Bank 1 Sensor 1)

Q: What does code P2245 mean?

O2 Sensor Reference Voltage Circuit Low (Bank 1 Sensor 1). P2245 means the engine computer has detected that the reference voltage circuit for the upstream oxygen sensor on bank 1 is lower than expected, which can prevent the sensor from producing a valid signal. The computer monitors this circuit and sets the code when the voltage on the reference line falls below a calibrated threshold for a set time.

P2245 means the engine computer has detected that the reference voltage circuit for the upstream oxygen sensor on bank 1 is lower than expected, which can prevent the sensor from producing a valid signal. The computer monitors this circuit and sets the code when the voltage on the reference line falls below a calibrated threshold for a set time.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Rough idle or hesitation during acceleration if the sensor signal is affected
Poor fuel economy due to incorrect air-fuel ratio feedback
Increased emissions or a failed emissions test
In rare cases, a stumble or surge while driving at steady speed

Common causes, most likely first

A short to ground or chafed wire in the sensor reference voltage circuit
Corroded or loose electrical connector at the oxygen sensor or engine computer
Failed oxygen sensor with an internal short in the reference circuit
Open or high-resistance ground connection for the sensor heater or signal return
Faulty engine computer driver for the reference voltage circuit, though uncommon
Contamination or damage to the sensor wiring from heat or debris

How to diagnose and fix it

Inspect the oxygen sensor connector and wiring for corrosion, chafing, or loose pins, and repair as needed
Check the reference voltage circuit for a short to ground using a digital multimeter and wiring diagram
Test the oxygen sensor heater and signal circuits for resistance and continuity against manufacturer specifications
Verify the sensor ground circuit is clean and tight, and clean or repair ground connections
If the circuit tests good, replace the bank 1 sensor 1 oxygen sensor with a quality direct-fit unit
Clear the code and perform a road test to confirm the repair, monitoring live data for proper sensor switching
If the code returns after sensor replacement, diagnose the engine computer reference voltage output and repair or replace as required

Reference voltage faults that fool sensor replacement

A chafed wire harness near the exhaust manifold often shorts the reference voltage to ground, and replacing the sensor will not fix the code until the harness is repaired.
The reference voltage circuit is shared internally in some engine computers, so a fault on one sensor circuit can affect others and set additional codes that point away from the real problem.
A poor engine ground can cause the reference voltage to read low at the computer even though the sensor and wiring test fine, so always verify ground integrity before condemning parts.
Some scan tools show a default or substitute value for the oxygen sensor when the reference circuit fails, which can mislead a technician into thinking the sensor is working normally.
After repairs, the code may not clear immediately because the computer runs a specific monitor that requires a complete drive cycle with steady cruise and idle periods.

Can I keep driving with P2245?

You can usually drive the vehicle with this code, but avoid aggressive acceleration and long trips until it is repaired because the engine may run rich or lean and damage the catalytic converter over time. If the check engine light begins flashing or you notice severe drivability problems, stop driving and have the vehicle towed.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.