OBD-II Diagnostic Trouble Code
P2031 — Exhaust Gas Temperature Sensor Bank 1 Sensor 2
P2031 is a general circuit fault for exhaust gas temperature sensor bank 1 sensor 2. The ECM saw a signal that was missing, implausible or did not match the other EGT sensors. Sensor 2 location varies by OEM; on most diesel trucks it sits between the DOC and DPF, where the ECM uses it to control and confirm regeneration.
Severity 3/5
Truck-relevant
Service this week
Severity
Service this week
Exhaust Gas Temperature Sensor Bank 1 Sensor 2
Code
P2031
Category
Powertrain
Subsystem
Aftertreatment
Truck-relevant
Yes
What this means for truckers
P2031 (Exhaust Gas Temp Sensor Bank 1 Sensor 2) — see existing.
Before you replace parts — try this first
P2031 on the Aftertreatment system is most often failed egt sensor (internal open or drift from heat cycling) — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
Check-engine light, and on most diesels the ECM stops or limits active DPF regeneration because it can no longer trust the temperature reading. Over time this can lead to soot loading warnings, forced regen requests and eventually a derate. Fuel economy may drop if the ECM uses default values.
Common causes
- CommonFailed EGT sensor (internal open or drift from heat cycling) ($150–$450)
- CommonHeat-damaged, melted or chafed sensor pigtail or harness near the exhaust ($100–$400)
- OccasionalCorroded or loose connector, often from road spray ($80–$250)
- OccasionalFault in the EGT sensor module on systems that route sensors through a separate module ($300–$900)
- RareECM internal fault ($1000–$2500)
How to fix
With the engine cold, compare all EGT readings on a scan tool; they should be close to ambient and to each other
When to use: First check to spot the sensor that disagrees
Inspect the sensor pigtail and harness along the exhaust for melted insulation, rubbing and broken clips
When to use: Before replacing any sensor, especially after recent exhaust or DPF work
Measure sensor resistance and compare to the OEM chart at the current temperature
When to use: To confirm a failed sensor versus a wiring problem
Replace the sensor using anti-seize on the threads and secure the pigtail away from hot surfaces
When to use: When the sensor is out of specification or the reading is erratic
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P2002 — Diesel Particulate Filter Efficiency Below Threshold (Bank 1)
- → P2003 — Diesel Particulate Filter Efficiency Below Threshold (Bank 2)
- → P2032 — Exhaust Gas Temperature Sensor Bank 1 Sensor 2 Low
- → P2033 — Exhaust Gas Temperature Sensor Bank 1 Sensor 2 High
- → P2080 — Exhaust Gas Temperature Sensor Circuit Range/Performance Bank 1 Sensor 1
Frequently Asked Questions
Can I drive with code P2031?
P2031 is severity 3 — plan service within a few days. Performance is likely degraded already (you may feel reduced power, harsher shifts, or slightly worse fuel economy). Continuing to drive risks additional damage to adjacent components.
How much does it cost to fix P2031 on a commercial truck?
Total repair cost ranges $80–$2500 depending on the root cause. The cheapest fix is usually the first one listed below — Failed EGT sensor (internal open or drift from heat cycling) — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P2031 fail a DOT inspection?
Yes — P2031 is an emissions-related code, and DOT inspectors check emissions compliance. An active emissions code with a check engine light can result in an out-of-service violation under FMCSA Part 393. The truck typically can't be moved until the code is cleared. Repeated emissions violations escalate to CSA scores.
What's the difference between P2031 and related codes?
P2031 is closely related to: P2002 (Diesel Particulate Filter Efficiency Below Threshold (Bank 1)), P2003 (Diesel Particulate Filter Efficiency Below Threshold (Bank 2)), P2032 (Exhaust Gas Temperature Sensor Bank 1 Sensor 2 Low), P2033 (Exhaust Gas Temperature Sensor Bank 1 Sensor 2 High). These codes share the same subsystem (aftertreatment) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P2031 is set without the companions, the issue is more isolated.
How do I prevent P2031 from coming back after a repair?
For P2031 (Exhaust Gas Temperature Sensor Bank 1 Sensor 2), prevention centers on the aftertreatment system. Run quality DEF (verify supplier — BlueDEF, PEAK, Yara Air1). Don't skip parked regens — when the dash asks for one, do it. Avoid extended idle time which fouls the DPF. Replace NOx sensors at the OEM interval (typically 400K miles).