Oxygen Sensor 2 Control and Trim Faults (26 codes)

What these codes mean

These 26 entries compare the positive-current, reference-voltage, negative-current and pumping-current-trim reports for the named Sensor 2 on Bank 1 or Bank 2. Each bank has three positive-current conditions, four reference conditions, three negative-current conditions and three trim conditions. The member list preserves every code, exact title, bank and reported condition; it does not count the installed sensors or identify a left/right location.

Identify the complete manufacturer DTC, reporting controller and installed sensing assembly before choosing a part. Sensor 2 in a generic descriptor is not enough to assume a conventional stand-alone rear oxygen sensor, a particular catalyst location or the same part on the opposite bank. A shared generic label does not establish interchangeable sensors, connectors or controller interfaces.

Current-control, reference, trim and heater functions need separate identification. Bosch’s LSU 4.9 documentation, for example, distinguishes pump current, virtual ground, Nernst voltage, heater connections and a connector trimming resistor. It also requires the appropriate evaluation interface. That component example is not a universal rear-sensor pinout, and a negative-current or reference label is not permission to bridge a terminal to chassis ground.

Keep general/circuit-open, low, high and reference-performance results distinct. They identify different monitored conditions; they do not create a universal resistance, voltage or short/open truth table. A performance report does not certify that every circuit is healthy. Apparent companion-bank agreement or a normal reading in one operating state does not prove the affected sensor, shared connections or receiving electronics are sound.

Trim concerns calibration used in interpreting the sensing function, rather than an independent declaration that the exhaust mixture is rich or lean. The Bosch connector resistor is one documented component design. Pico’s equipment-specific pre-catalyst LSU 4.2 example likewise distinguishes the connector calibration from the connected circuit and restricts the measurement equipment and test conditions. Do not transfer either example’s pins, resistance values or test sequence to another installation, splice a calibration connector or use one unplugged reading as a universal parts verdict.

A concrete GM example shows why the installed assembly matters. The cited 2021 Tahoe NOx Sensor 2 procedure, document 5504091, groups P22AB/P22AC/P22AD/P22B2/P22B6/P22B7 with NOx Sensor 2. The described assembly supplies wide-band and digital-lambda information as well as NOx information, with a sensor-calibrated module communicating over serial data. Its P22B6/P22B7 checks run continuously after the specified engine, heater and supply prerequisites. Identify the actual sensing and control assembly rather than assuming the generic title always names a separate rear oxygen sensor.

Software and hardware also require separate evidence. GM’s April 2025 bulletin 24-NA-094 includes the low/high trim pair among possible software-anomaly reports for its listed 2024 Silverado 1500/Sierra 1500 3.0L applications. The bulletin provides an applicable-calibration or service-diagnosis branch. A dated bulletin is a reason to check the exact vehicle’s applicability and current service instructions, rather than proof that any sensor, harness or module must be replaced or updated.

Save the full scan, status, event data and recent sensor, exhaust, wiring or programming history before clearing anything. Preserve heater, reference, communication, mixture and catalyst reports together; several codes do not prove one shared fault, and an absent opposite-bank code does not establish a healthy comparison bank. Have qualified personnel identify the actual interface, use the prescribed cooling, isolation and protected checks, and verify the demonstrated repair. Do not inject current, attach a generic test lamp, heat or spray a live harness, exchange bank connectors or reproduce the fault through an improvised drive cycle.

Judge urgency from actual warnings and symptoms. Sensor numbering does not guarantee unchanged fuel control, harmless driving, inevitable damage or a particular inspection result. Stop safely and obtain assistance for severe running problems, unsafe power loss, overheating, flashing warnings or exhaust fumes. Request a diagnosis-first estimate that names the confirmed circuit, module or serviceable assembly and required verification; the code does not supply a reliable parts price.