Let's break that down:
* PO: This indicates a Powertrain Diagnostic Trouble Code (DTC).
* 156: This specific code is related to the oxygen sensor.
* Bank 2: Refers to the side of the engine that doesn't contain cylinder #1. V6 engines typically have two banks of cylinders.
* Sensor 1: This is the oxygen sensor located before the catalytic converter.
Essentially, the code means the heater element within the oxygen sensor on Bank 2, Sensor 1, isn't working correctly. The heater is crucial because it warms the sensor up quickly, allowing for more accurate readings, especially during cold engine starts. A malfunctioning heater can lead to a delayed or inaccurate reading from the oxygen sensor which the engine's computer uses for fuel control and emissions. This might result in poorer fuel economy, rough running, or a failing emissions test.
Possible causes:
* Faulty oxygen sensor: The sensor itself might be bad and need replacement.
* Wiring problem: A broken wire, short circuit, or poor connection in the oxygen sensor heater circuit. This often requires tracing the wiring harness.
* Faulty PCM (Powertrain Control Module): Less common, but a problem with the engine computer itself is a possibility. This is usually diagnosed after other components have been checked.
You'll likely need a mechanic to properly diagnose the root cause. Simply replacing the oxygen sensor might not solve the problem if the underlying issue is a wiring fault or a problem with the PCM.
