Q: Can I drive with B1549 active?

In most cases, yes — but the affected system may not operate correctly. Diagnose and fix promptly.

Q: How much does it cost to fix B1549?

Component replacement typically costs $30–$250. 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. ---

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 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.

DTC B1549: B1549 — PATS Received Invalid Format Of Key-Code From Ignition Key Transponder: Causes, Symptoms & Fix

The B1549 OBD2 fault code relates to the PATS Received Invalid Format Of Key-Code From Ignition Key Transponder circuit. When the circuit circuit failure, the module cannot properly monitor or control this body system. At AIscanAuto, we help drivers quickly identify OBD2 trouble codes, understand their root causes, and find the right fix.

B1549 — PATS Received Invalid Format Of Key-Code From Ignition Key Transponder: Causes, Symptoms & Fix

The B1549 OBD2 fault code relates to the PATS Received Invalid Format Of Key-Code From Ignition Key Transponder circuit. When the circuit circuit failure, the module cannot properly monitor or control this body system.

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

Symptoms

Starting difficulties
Tachometer erratic or not working
Dashboard warning lights
Possible stalling

Common Causes

Faulty component — internal damage or wear affecting PATS Received Invalid Format Of Key-Code From Ignition Key Transponder
Wiring issues — broken, corroded, or chafed wires in the circuit
Connector problems — loose, oxidized, or moisture-damaged pins
a general circuit failure is detected — can result from wiring faults, connector issues, or component failure
Module input failure — rare, but the control module input stage may be defective

Step-by-Step Diagnosis

Scan with OBD2 tool — Confirm B1549 is active. Check for additional DTCs.
Visual inspection — Examine the PATS Received Invalid Format Of Key-Code From Ignition Key Transponder wiring and connector for corrosion or damage.
Check voltage and ground — Use a multimeter to verify proper reference voltage.
Test component — Compare readings to factory specs. A stuck or erratic signal confirms failure.
Check for shorts/opens — Perform continuity tests on the wiring between the component and control module.

Repair & Solutions

If the component is defective, replace the PATS Received Invalid Format Of Key-Code From Ignition Key Transponder 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 component replacement, inspect the control module connector.

Related Codes

B1546 — Passenger's Seatback Autoglide Forward Switch Circuit Short to Ground
B1547 — PATS Ignition Key Transponder Signal Is Not Received
B1548 — PATS Received Incorrect Key-Code From Ignition Key Transponder

DTC B1549: B1549 — PATS Received Invalid Format Of Key-Code From Ignition Key Transponder: Causes, Symptoms & Fix

B1549 Diagnostic Trouble Code