What does a dtc code p0135 mean?

A DTC code P0135 indicates a malfunction in the oxygen sensor heater circuit, specifically for the oxygen sensor located in bank 1, sensor 1. This sensor is crucial for monitoring exhaust gases and helping manage the engine's air-fuel mixture. A problem with this code may lead to poor fuel economy and increased emissions. Common causes include a faulty sensor, wiring issues, or problems with the engine control module (ECM).