P2C62 O2 Sensor Pumping Current Trim Circuit/Open Bank 1 Sensor 3

P2C62 points to an open trim circuit at the third oxygen probe of bank 1. Wide-band probes such as Bosch's LSU 4.9 carry a trimming resistor in the connector on a pin of its own (RT/IA) that sets each probe's characteristic; the engine module reads it to scale the pump current, so with the lead broken the signal still moves but with the wrong gain. A third probe sits behind a second catalyst, on diesels typically after the SCR stage. No carmaker documents P2C62 publicly: GM's 3.0L Duramax tables and bulletins use only P2C63, P2C64 and P2C65 for sensor 3. CARB requires circuit continuity checks on oxygen and air-fuel sensors. The front and middle analogues are P2626 and P22B5; low and high faults of this probe are P2C63/P2C64.

Likely causes

Symptoms

• MIL on, usually without noticeable driving change
• Catalyst or aftertreatment monitors not completing

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: bosch-motorsport.com, law.cornell.edu, gsi.ext.gm.com.