P246A Exhaust Gas Temperature Sensor Circuit Intermittent/Erratic (Bank 2 Sensor 3)

P246A flags a third bank 2 exhaust temperature probe whose reading jumps from sample to sample faster than real gas temperature could, even though every single value stays inside the legal range. The bank 2 code itself is not described by any manufacturer in public material. GM's diesel tables run the equivalent quick-change test for other probes every 100 ms: the 2025 tables count a step above 100 °C between samples, fail after 12 of 25 samples and confirm the fault in a second trip (Type B). CARB expects such erratic-signal checks on emission inputs. Loose terminals, corroded pins and harness strands weakened by heat and vibration are the usual reasons, sometimes a cracked sensor element. A steady but wrong value is P2467, a permanent short or open P2468 or P2469.

Likely causes

Symptoms

• MIL on after a repeated fault
• Temperature trace jumps in live data
• Fault may come and go with bumps or engine heat

Repair estimate

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

Parts involved

Related codes

References: law.cornell.edu, gsi.ext.gm.com.