What does code P2A09 mean?

Q: What does code P2A09 mean?

O2 Sensor Negative Voltage Bank 2 Sensor 1. P2A09 indicates that the powertrain control module (PCM) has detected a negative voltage signal on the upstream oxygen sensor for bank 2, which monitors the exhaust from the side of the engine that does not contain cylinder number one. The PCM expects the sensor's signal voltage to swing between approximately 0.1 and 0.9 volts, so a reading that drops below zero volts is physically impossible for a properly functioning sensor and triggers this fault.

DTC codes / P2Axx · Hybrid propulsion / P2A09

P2A09O2 Sensor Negative Voltage Bank 2 Sensor 1

P2A09 indicates that the powertrain control module (PCM) has detected a negative voltage signal on the upstream oxygen sensor for bank 2, which monitors the exhaust from the side of the engine that does not contain cylinder number one. The PCM expects the sensor's signal voltage to swing between approximately 0.1 and 0.9 volts, so a reading that drops below zero volts is physically impossible for a properly functioning sensor and triggers this fault.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.