This code indicates that the engine computer has detected a lower-than-expected current in the heater control circuit for the upstream oxygen sensor on Bank 2 (the side of the engine opposite cylinder #1). The heater element is needed to bring the sensor to operating temperature quickly; a low-current reading typically points to an open or high-resistance condition in that circuit. Bank 2 Sensor 1 is the pre-catalytic converter sensor on the Bank 2 side.
The internal heater element inside the sensor can burn out or develop high resistance over time, causing the PCM to detect low current in the control circuit. This is the most common cause for this code.
Chafed, broken, or corroded wiring between the sensor and the PCM can create an open circuit or high-resistance condition that results in low current being detected. Heat shielding areas and connector pins are common failure points.
The electrical connector at the oxygen sensor can accumulate corrosion, moisture, or lose pin tension, creating a poor connection that limits current flow in the heater circuit.
Some vehicles supply the O2 sensor heater through a dedicated fuse or relay. An open fuse or failed relay can cause low current on the control side of the circuit.
A failure in the PCM's internal driver circuit for the sensor heater is possible but uncommon. This should only be considered after all wiring, connector, and sensor possibilities have been thoroughly ruled out.
The vehicle is usually drivable, but the engine may run less efficiently, especially when cold, and fuel economy can suffer. The code will also cause an emissions test failure in most jurisdictions, so it should be addressed promptly.
Often yes, but not always. A failed heater element in the sensor is the most common cause, but wiring damage, connector corrosion, or a blown fuse can produce the same code. Proper diagnosis is needed before replacing parts.
No, that is almost never the correct fix. PCM failures are extremely rare for this code. The sensor itself, wiring, or connectors are the overwhelmingly likely culprits. Replacing the PCM without exhaustively ruling out all other causes is a mistake.
Bank 2 is the side of the engine that does not contain cylinder #1. Sensor 1 is the upstream oxygen sensor, located before the catalytic converter in the exhaust manifold or downpipe on that side.