Subaru Error Code P1571: How to Fix It

Q: Is it safe to drive with Subaru error code P1571?

Yes, P1571 is generally safe to drive with as it relates to diagnostic test mode communication rather than critical engine functions. However, it may prevent proper diagnostic testing if other issues arise, so it should be fixed promptly.

Q: What causes Subaru P1571 error code?

P1571 is typically caused by poor electrical connections, corroded ground points, low battery voltage, damaged wiring in the diagnostic circuit, or rarely, a faulty ECU. Most cases are resolved by cleaning connections and checking battery health.

Q: How much does it cost to fix P1571 on a Subaru?

If it's a simple connection issue, the fix costs nothing but your time. Professional diagnosis typically runs $100-150. If wiring repair or ECU replacement is needed, costs can range from $200-800 depending on the specific problem.

Q: Will P1571 cause my Subaru to fail emissions testing?

Potentially yes. While P1571 doesn't directly affect emissions, it can prevent the OBD2 system from completing required readiness monitors, which may cause an emissions test failure until the code is resolved.

Q: Can a bad battery cause P1571 in Subaru vehicles?

Yes, a weak or failing battery that provides inconsistent voltage can trigger P1571. The ECU requires stable power to maintain proper communication with diagnostic systems, so battery health is crucial for preventing this code.

Abstract

Subaru error code P1571 indicates a problem with the test mode signal circuit in your vehicle's engine control system. This diagnostic trouble code typically appears when the ECU detects an issue with the test mode communication between components. While not immediately dangerous to drive with, this code should be addressed to ensure proper engine diagnostics and performance.