The B1220 OBD2 fault code relates to the Fuel Tank Pressure Sensor circuit. This sensor monitors fuel tank pressure for evaporative emissions control. When the circuit open circuit, the ECM cannot verify the EVAP system integrity.

At AIscanAuto, we help drivers quickly identify OBD2 trouble codes, understand their root causes, and find the right fix.

Symptoms

• Check Engine Light illuminated
• Failed emissions test
• Possible fuel odor
• EVAP system not testing properly

Common Causes

• Failed pressure sensor — internal damage
• an open circuit is detected — indicates a break in the circuit path, resulting in no signal transmission
• Wiring issues — damaged harness
• Connector problems — corrosion

Step-by-Step Diagnosis

1. Scan with OBD2 tool — Confirm B1220.
2. Visual inspection — Check sensor and wiring.
3. Test sensor output — Compare to specs.
4. Smoke test EVAP system — Check for leaks.

Repair & Solutions

• Replace sensor if faulty.
• Repair wiring.
• Clear code and test EVAP.

Related Codes

• B1217 — Horn Relay Coil Circuit Failure
• B1218 — Horn Relay Coil Circuit Short to Vbatt
• B1219 — Fuel Tank Pressure Sensor Circuit Failure

External References

- OBD2Pros — Complete DTC Reference

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.