P2231Generic code

P2231 Code: O2 Sensor Signal Circuit Shorted to Heater Circuit (Bank 1 Sensor 1)

The P2231 code means the signal wire of the bank 1 sensor 1 oxygen sensor is in contact with the heater circuit, so the signal is corrupted and the sensor cannot measure. The usual cause is an internal short in the sensor. The engine runs, but fuel use goes up until it is repaired.

Severity
Medium
Can I keep driving?
Yes, no immediate risk
Estimated cost
$50 to $250
Difficulty
Easy
System
Air and Fuel
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P2231 code means

An oxygen sensor has an internal heater fed with 12 V and a signal wire that carries a very low voltage. If the computer sees the signal following the changes in the heater, it concludes there is a short between the two.

This usually happens inside the sensor from internal deterioration, or at the connector when water gets in. Wiring melted by the exhaust can also join the two wires.

The P2231 code is about the bank 1 sensor 1 position, the sensor ahead of the catalytic converter, so it directly affects mixture control and fuel economy.

P2231 code symptoms

  • Check engine light on.
  • Higher fuel use.
  • A heater code for the same sensor may be stored along with it.

Likely causes of the P2231 code

  1. Internal short in the sensor. The most common cause.
  2. Water or corrosion in the connector. Check the lock, the pins and whether there is moisture or corrosion.
  3. Wiring melted or rubbed by the exhaust.

How to diagnose the P2231 code step by step

  1. Inspect the connector and the wiring.
  2. Unplug the sensor and measure between the signal and heater pins on the sensor side. There should be no continuity.
  3. Check the harness side. There should be no continuity between those wires either.

How to fix the P2231 code

  • Replace the sensor if it has the internal short.
  • Repair the wiring or the connector.
  • Clear the codes and verify.

After the repair, drive the vehicle through a full warm-up and make sure the P2231 code stays away and the sensor signal behaves normally.

Technical reference data

  • Resistance between the signal and the heater in a healthy sensor: infinite.
  • These are reference values only: check the manufacturer data for your vehicle.

Brand-specific notes

This code shows up on several makes, and the internal short in the sensor is the first thing to rule in or out.

P2231 on Toyota

Frequent on Toyota vehicles.

P2231 on Volkswagen

Frequent on Volkswagen vehicles.

P2231 on Audi

Frequent on Audi vehicles.

Frequently asked questions about P2231

Can I drive with a P2231 code?
Yes. The engine keeps running, but the mixture is controlled less accurately and fuel use goes up, so do not put the repair off for long.
Does the sensor have to be replaced?
Almost always yes, when the short is inside the sensor. A short in the connector or wiring is the exception.
Can it damage the computer?
It is uncommon, but it is best to repair it soon.
How much does it cost to fix P2231?
Roughly $50 to $250. A sensor with labor is the usual cost, and a connector repair costs less.
What does the P2231 code mean?
It is a generic OBD2 code that means the signal circuit of the bank 1 sensor 1 oxygen sensor is shorted to its heater circuit. The signal is corrupted and the sensor cannot measure the exhaust.
Will a P2231 code clear itself?
It is unlikely. A short inside the sensor or in the wiring does not go away on its own, so the code returns until the cause is repaired.
What is the most common cause of P2231?
An internal short in the oxygen sensor. Water or corrosion in the connector and wiring melted by the exhaust are the other causes.

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Questions about the P2231 code

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