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

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.

Bank 2 is the side without cylinder 1, so it only exists on V or boxer engines.

Symptoms

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

Most likely causes

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

What to check, in order

Start with the simplest. You can tick off each step.

1. Read the soot load and differential pressure with a scanner
2. Gently move the wiring with the engine running and watch whether the reading changes.
3. Check the differential pressure sensor's hoses
4. Check the temperatures before and after the filter
5. Fix any fuel injection or EGR codes before regenerating
6. Perform a regeneration while driving or at a repair shop when the diagnosis allows it

Good to know

• Repair difficulty: medium
• It affects emissions.

What each character of P2477 means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 4: Emissions
• 77: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2477?

If the light is on steadily, take a highway drive or go to a repair shop soon. If the car is in limp mode or the light is flashing, do not push the engine.

What causes code P2477?

The most common causes are: loose or corroded pins in the probe connector; wire strands breaking near the hot pipe; cracked probe element with unstable contact.

Related codes

• P2473Exhaust Gas Temperature Sensor Circuit (Bank 2 Sensor 4)
• P2474Exhaust Gas Temperature Sensor Circuit Range/Performance (Bank 2 Sensor 4)
• P2475Exhaust Gas Temperature Sensor Circuit Low (Bank 2 Sensor 4)
• P2476Exhaust Gas Temperature Sensor Circuit High (Bank 2 Sensor 4)
• P2472Exhaust Gas Temperature Sensor Circuit Intermittent/Erratic (Bank 1 Sensor 4)
• P246AExhaust Gas Temperature Sensor Circuit Intermittent/Erratic (Bank 2 Sensor 3)

Sources

• law.cornell.edu: 13 CCR 1968.2
• gsi.ext.gm.com: 17OBDG04 Engine Diagnostics

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.