P2031Generic code

P2031 Code: Exhaust Gas Temperature Sensor Circuit (Bank 1 Sensor 2)

The P2031 code means the computer found an electrical fault in the circuit of the exhaust gas temperature (EGT) sensor, bank 1 sensor 2. The main effect is that the computer may cut engine power or suspend particulate filter regenerations. You can drive with caution, but have it checked soon.

Severity
Medium
Can I keep driving?
Yes, but with caution
Estimated cost
$60 to $250
Difficulty
Medium
System
Emissions Control
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P2031 code means

EGT sensors measure the exhaust temperature ahead of the turbo, the catalytic converter or the particulate filter. The computer uses them to protect the turbo and the catalytic converter and to control the regeneration of the particulate filter.

The sensor changes its resistance with temperature, and the computer measures the resulting voltage. The P2031 code is a circuit fault, and it can come from the sensor, from the wiring or from the power supply to the sensor.

Most of these are thermistors or thermocouples that work up to about 900 °C (1,652 °F). On these codes, sensor 1 is usually the one closest to the engine. See the EGT sensor guide for how to test one.

Always start with the simple things: the fuse, the relay and the connector. Then check power, ground and signal with the component plugged in, using back-probes. Last, test the continuity of each wire all the way to the computer. Only when all of that checks out should you replace the component.

P2031 code symptoms

  • Check engine light on.
  • The computer may reduce engine power or suspend particulate filter regenerations.

Likely causes of the P2031 code

  1. Damaged or corroded connector. The most frequent cause.
  2. Wiring cut or shorted between the sensor and the computer.
  3. Failed sensor. Open, or shorted inside.
  4. Missing reference supply. Check whether other sensors are also failing.
  5. Computer. Uncommon, so rule out everything above first.

How to diagnose the P2031 code step by step

  1. Read the sensor value on the scan tool and compare it with what you expect.
  2. Inspect the connector for corrosion, water or loose pins.
  3. Check power and ground with the key on: the reference should be correct and the voltage drop on the ground should be under 0.1 volt.
  4. Measure the signal with the connector plugged in and see whether it changes with the condition.
  5. Do a wiggle test on the harness with the scan tool in graph mode.
  6. Check the continuity of each wire to the computer. It should be under 1 ohm.

How to fix the P2031 code

  • Repair the connector or the wiring.
  • Replace the sensor if the tests confirm it is bad.
  • Correct the real condition if there is one.
  • Clear the codes and verify the repair with a road test.

Technical reference data

  • Resistance at room temperature: about 200 ohms on many PTC sensors. It varies by type.
  • Working range: -40 to 900 °C (-40 to 1,652 °F).
  • These values are only a guide, so look up the manufacturer data for your vehicle.

Brand-specific notes

Short city trips are the main enemy of the particulate filter, whatever the brand. The source lists these codes as frequent on the diesel vehicles below.

P2031 on Volkswagen, Audi and SEAT

This code is frequent on diesel Volkswagen, Audi and SEAT models.

P2031 on Peugeot, Citroen and Renault

This code is frequent on diesel Peugeot, Citroen and Renault models.

P2031 on Ford

This code is frequent on diesel Ford models.

P2031 on Mercedes-Benz and BMW

This code is frequent on diesel Mercedes-Benz and BMW models.

P2031 on Toyota Hilux, Nissan Navara and Chevrolet

This code is also frequent on the Toyota Hilux, the Nissan Navara and diesel Chevrolet models.

Frequently asked questions about P2031

Can I drive with a P2031 code?
With caution. It can limit engine power or keep the particulate filter from regenerating.
Does the sensor have to be replaced?
Only if the tests confirm it. The connector and the wiring fail just as often as the sensor.
What does the B1S2 EGT sensor do?
EGT sensors measure the exhaust temperature ahead of the turbo, the catalytic converter or the particulate filter. The computer uses them to protect the turbo and the catalytic converter and to control the regeneration of the filter.
How much does it cost to fix P2031?
Roughly $60 to $250, depending on whether it is a connector, a wire or the sensor.
What does the P2031 code mean?
It is a generic OBD2 code for an electrical fault in the circuit of the exhaust gas temperature sensor on bank 1, sensor 2. The cause can be the sensor, the wiring or the power supply.
Will a P2031 code clear itself?
Only if the cause was a passing glitch. A damaged connector or a broken wire will bring the P2031 code back.
What is the most common cause of P2031?
A damaged or corroded connector. Wiring between the sensor and the computer is the next place to look, before you buy a sensor.

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