Fault codeP2031

MODERATE

Exhaust Gas Temperature Sensor Circuit (Bank 1 Sensor 2)

What this code means

Exhaust Gas Temperature Sensor Circuit (Bank 1 Sensor 2).

“Bank 1” is the side of the engine that holds cylinder number 1; “Bank 2” only exists on V and flat engines. An in-line engine has a single bank.

P2031 is a generic code: it means the same thing on every make. P2031 belongs to family P20xx — Fuel, air and emission controls. Its page explains how to read a code and groups all its codes by part.

Type of fault

The control unit has detected an electrical anomaly on this circuit without saying exactly which. Diagnosis starts with a visual check of the wiring and connector, then measuring the component — resistance, supply, ground — with a multimeter.

Exhaust gas temperature sensor

Exhaust temperature sensors, often several on a diesel, measure the heat of the gases before the turbo, the catalytic converter or the particulate filter. The control unit uses them to protect the turbo and to manage the particulate filter regenerations.

What you notice

Often nothing; sometimes limp mode, or particulate filter regenerations that no longer happen.

How to check it

These sensors live in extreme heat and their wire often breaks near the exhaust. Check the connector and the wiring, then the sensor's resistance, comparing it with an identical sensor if there is one. Engine cold and stopped, every exhaust temperature should read about the same as the outside temperature.

Watch it live in Klaro

With an OBD2 adapter plugged in, these live readings show the part at work, when your car reports them:

Exhaust gas temperature, bank 1 sensor 1
Exhaust gas temperature, bank 1 sensor 2
DPF inlet temperature, bank 1

What to do

Have it checked this week. The car remains usable, but the fault will not clear itself and will fail the roadworthiness test.

Clearing a code switches the light off but repairs nothing: if the fault remains, the code comes back. Clearing a fault code yourself →

How to read this code

PPowertrain
2standardised code
0Fuel, air and emission controls
31P2031