Failed oxygen sensor heater element (open circuit inside the sensor); Damaged or corroded wiring or connector at the oxygen sensor heater circuit; Blown fuse or fusible link supplying power to the oxygen sensor heater; Faulty oxygen sensor heater relay (where equipped); Poor ground connection for the heater circuit; PCM internal driver failure for the heater control circuit (rare)

DTC codes / GM codes / P1031

P1031 · GMO2 Sensor Heater Control Circuit Problem

Q: What does code P1031 mean?

O2 Sensor Heater Control Circuit Problem. P1031 on a GM vehicle means the powertrain control module has detected an abnormal condition in the heater circuit for a heated oxygen sensor, typically an open, short, or excessive current draw on the heater element or its wiring. The computer monitors the heater control circuit and flags this code when the voltage or current feedback does not match what it expects during the heater warm-up phase.

P1031 on a GM vehicle means the powertrain control module has detected an abnormal condition in the heater circuit for a heated oxygen sensor, typically an open, short, or excessive current draw on the heater element or its wiring. The computer monitors the heater control circuit and flags this code when the voltage or current feedback does not match what it expects during the heater warm-up phase.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering and auxiliary emission controls

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Extended time before the engine enters closed-loop fuel control, causing slightly rough idle when cold
A slight decrease in fuel economy, especially during short trips
Occasional hesitation or stumble during cold start and initial acceleration
In some cases, a stored pending code without the light if the fault is intermittent

Common causes, most likely first

Failed oxygen sensor heater element (open circuit inside the sensor)
Damaged or corroded wiring or connector at the oxygen sensor heater circuit
Blown fuse or fusible link supplying power to the oxygen sensor heater
Faulty oxygen sensor heater relay (where equipped)
Poor ground connection for the heater circuit
PCM internal driver failure for the heater control circuit (rare)

How to diagnose and fix it

Inspect the oxygen sensor heater fuse and replace if blown, then recheck for the code
Visually inspect the sensor connector and wiring for corrosion, chafing, or loose pins
Measure resistance across the heater element at the sensor connector and compare to specification
Check for battery voltage at the heater power supply circuit with the key on
Test the heater control circuit for continuity to the PCM and for short to ground or power
If wiring and fuse are good, replace the oxygen sensor with a quality OEM or equivalent part
Clear codes and verify the heater circuit operates correctly during a cold start and test drive

Heater circuit checks before sensor replacement

A blown heater fuse often points to a shorted oxygen sensor heater element, so replacing only the fuse without checking the sensor will likely blow the new fuse immediately.
The heater circuit is only active during cold start and warm-up, so an intermittent P1031 may not reappear on a warm engine and requires a cold-soak test to confirm.
Corrosion inside the sensor connector can mimic a failed heater element, and a simple resistance check at the sensor pigtail versus at the PCM can isolate whether the fault is in the sensor or the harness.
On some GM platforms, a faulty heater circuit can cause the sensor to stay cold and report a lazy signal, leading to a false lean or rich code that disappears once the heater fault is repaired.
The PCM may set P1031 without illuminating the check engine light on the first occurrence, so always check for pending codes when diagnosing driveability complaints.

Can I keep driving with P1031?

You can generally continue driving with P1031, but avoid extended idling and short trips until repaired because the engine may run in open-loop longer and waste fuel. If the check engine light flashes or you notice rough running, have it diagnosed promptly.

Tools that help

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Guidance is general and written for GM vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.