P20E2: Exhaust Gas Temperature Sensor 1/2 Correlation (Bank 1)

P20E2 flags that bank 1 exhaust temperature sensors 1 and 2 disagree at a moment when both should show nearly the same value. Sensor 1 usually sits ahead of the oxidation catalyst and sensor 2 behind it. GM runs this check on the 6.6 L Duramax LML/LGH (table 15OBDG09) and on the diesel of table 15OBDG04: after at least 28,800 s (8 h) with the engine off, the two readings captured at start-up are compared, and a gap above a limit taken from a look-up table counts as a Type B fault, so the MIL lights after two failing trips. A sensor that is offset but still inside its valid voltage window passes the circuit checks P0544 and P2031–P2033 and is only caught here. Drivers rarely notice more than the lamp, although GM blocks some regeneration functions while this code is active.

Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank.

Symptoms

• Malfunction indicator lamp on, often with no change in driving
• Particulate filter regeneration delayed or blocked
• Code returns after a long parking period

Most likely causes

• Exhaust temperature sensor 1 or 2 drifted or aged (offset reading)
• Corroded or loose connector adding resistance to one sensor signal
• Sensors swapped or a non-matching replacement part installed
• Engine control software needing an update

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. Compare both signals at the same time in live data and check any recent installation work.
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 P20E2 means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 0: Subsystem depends on the code range
• E2: Specific fault in that system

Frequently asked questions

Can I keep driving with code P20E2?

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 P20E2?

The most common causes are: exhaust temperature sensor 1 or 2 drifted or aged (offset reading); corroded or loose connector adding resistance to one sensor signal; sensors swapped or a non-matching replacement part installed.

Related codes

• P20E3Exhaust Gas Temperature Sensor 1/3 Correlation (Bank 1)
• P20E4Exhaust Gas Temperature Sensor 2/3 Correlation (Bank 1)
• P20E5Exhaust Gas Temperature Sensor 1/2 Correlation (Bank 2)
• P2080Exhaust Gas Temperature Sensor Circuit Range/Performance (Bank 1 Sensor 1)
• P2084Exhaust Gas Temperature Sensor Circuit Range/Performance (Bank 1 Sensor 2)
• P0544Exhaust Gas Temperature Sensor Circuit Bank 1 Sensor 1
• P2031Exhaust Gas Temperature Sensor Circuit (Bank 1 Sensor 2)

Sources

• gsi.ext.gm.com: 15OBDG09 Engine Diagnostics
• gsi.ext.gm.com: 15OBDG04 Engine Diagnostics
• patents.google.com: en

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.