Q: Can I drive with B1223 active?

Yes, in most cases — but the ECM may run in a default fuel temperature mode, slightly affecting efficiency.

Q: How much does it cost to fix B1223?

Sensor replacement typically costs $30–$150. DIY diagnosis with a multimeter can save on labor.

Q: Will the Check Engine Light go off on its own?

If the fault is intermittent, the light may turn off after several drive cycles. However, the underlying issue should still be addressed.

DTC B1223: B1223 — Fuel Temperature Sensor #1 Circuit Open: Causes, Symptoms & Fix

The B1223 OBD2 fault code relates to the Fuel Temperature Sensor #1 circuit. This sensor monitors fuel temperature and sends data to the engine control module (ECM) or body control module (BCM). When the circuit open circuit, the module cannot read accurate temperature values, which may affect fuel delivery calculations and emissions control. At AIscanAuto, we help drivers quickly identify OBD2 trouble codes, understand their root causes, and find the right fix — without the guesswork.

B1223 — Fuel Temperature Sensor #1 Circuit Open: Causes, Symptoms & Fix

The B1223 OBD2 fault code relates to the Fuel Temperature Sensor #1 circuit. This sensor monitors fuel temperature and sends data to the engine control module (ECM) or body control module (BCM). When the circuit open circuit, the module cannot read accurate temperature values, which may affect fuel delivery calculations and emissions control.

At AIscanAuto, we help drivers quickly identify OBD2 trouble codes, understand their root causes, and find the right fix — without the guesswork.

Symptoms

Check Engine Light (CEL) illuminated on the dashboard
Inaccurate or erratic fuel temperature readings
Possible fuel delivery issues in extreme temperatures
ECM may adjust fuel mixture incorrectly
Hard starting or poor performance in cold/hot weather

Common Causes

Faulty temperature sensor — internal damage or contamination
Wiring issues — broken, corroded, or chafed wires in the sensor circuit
Connector problems — loose, oxidized, or moisture-damaged pins
an open circuit is detected — indicates a break in the circuit path, resulting in no signal transmission
Open circuit — complete wire break interrupting signal path
Module input failure — rare, but the ECM/BCM input stage may be defective

Step-by-Step Diagnosis

Scan with OBD2 tool — Confirm B1223 is active. Check for additional DTCs.
Visual inspection — Examine the Fuel Temperature Sensor #1 wiring and connector for corrosion or damage.
Check voltage and ground — Use a multimeter to verify proper reference voltage.
Test sensor resistance — Compare readings to factory specs. A stuck or erratic signal confirms failure.
Check for shorts/opens — Perform continuity tests on the wiring between the sensor and control module.

Repair & Solutions

If the sensor is defective, replace the Fuel Temperature Sensor #1 with an OEM or quality aftermarket part.
Repair any damaged wiring or connectors using proper methods.
Clear the DTC with an OBD2 scanner and test drive to verify the code does not return.
If the code persists after sensor replacement, inspect the ECM/BCM connector.

Related Codes

B1220 — Fuel Tank Pressure Sensor Circuit Open
B1221 — See Manufacturer
B1222 — Fuel Temperature Sensor #1 Circuit Failure

External References

About This Guide

This diagnostic article is an original guide created by AIscanAuto for educational and troubleshooting purposes. The technical information about OBD2 DTC codes is based on publicly available automotive diagnostic standards and industry best practices. External links provided in the "External References" section are for additional reading and context only — they do not imply endorsement or ownership of third-party content. All repair procedures should be performed by qualified technicians.