Powertrain, generic (extended)

P2477 Exhaust Gas Temperature Sensor Circuit Intermittent/Erratic (Bank 2 Sensor 4)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2477 targets a signal from bank 2 probe 4 that jumps around, while each individual sample may still be in range. Real exhaust temperature changes only gradually because the probe and pipe have thermal mass, so sudden steps between consecutive readings betray a wiring or contact issue. GM documents the method for the bank 1 sibling P2472: its 2017 diesel table counts samples with a resistance step above 10 ohms and fails at 15 of 30, as a Type B fault with the MIL on the second trip. P2477 itself appears in no public maker document. Faults tend to come and go with vibration or heat, so wiggling the harness while watching live data is the usual way to find them.

Likely causes

Loose or corroded pins in the probe connector
Wire strands breaking near the hot pipe
Cracked probe element with unstable contact

Symptoms

  • MIL on after the second faulty trip
  • Value of bank 2 probe 4 jumps in live data
  • Fault code returns after being cleared

Repair estimate

DifficultyMediumDIY possible
Parts and labour€0–350
Time0.3–2 h

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

Parts involved

egt sensor b2s4egt wiring

Related codes

P2473P2474P2475P2476P2472P246A

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