P0043

Severity: Low

HO2S Heater Control Circuit Low (Bank 1 Sensor 3)

Last updated: July 2026

System

Powertrain

Subsystem

Fuel & Air Metering / Auxiliary Emissions

Code Type

Generic (SAE)

What does P0043 mean?

P0043 is a generic (SAE) powertrain diagnostic trouble code. It is defined as "HO2S Heater Control Circuit Low (Bank 1 Sensor 3)". It falls under the fuel & air metering / auxiliary emissions area of the vehicle’s powertrain system, and has the same core meaning across most makes and models.

When is P0043 set?

The onboard diagnostic system sets P0043 when it detects a condition matching "ho2s heater control circuit low (bank 1 sensor 3)" in the fuel & air metering / auxiliary emissions circuit or system. When the fault is confirmed, the module stores the code and, in most cases, turns on a warning light.

This code is generally minor and often relates to a signal, range or performance condition. It should still be inspected, especially if it returns after clearing.

Common symptoms

Check engine light (MIL) illuminated
Rough running, hesitation or loss of power
Increased fuel consumption
Difficulty starting or stalling

Possible causes

A failing or contaminated sensor in the affected circuit
Wiring, connector or ground problems
Vacuum, intake or exhaust leaks
A worn or failing mechanical component
Occasionally, a fault in the control module itself

What to check first

Scan for all stored and pending codes and note the freeze-frame data
Inspect the wiring and connectors for the affected circuit
Check for related leaks, loose components or obvious damage
Test the relevant sensor and its reference/ground with a meter
Clear the code and retest to see whether it returns

Frequently asked questions

What does the P0043 code mean?

P0043 means "HO2S Heater Control Circuit Low (Bank 1 Sensor 3)". It is a generic powertrain trouble code in the fuel & air metering / auxiliary emissions area.

Is it safe to drive with a P0043 code?

This code is usually minor, and short-distance driving is often possible, but you should still have it checked — especially if the warning light stays on or the code returns.

How do I fix a P0043 code?

There is no single fix. Start by confirming the code with a scan tool, then work through the likely causes and checks above — inspecting wiring, connectors and the relevant components before replacing any parts. On most vehicles, confirm the diagnosis before repairs.

Can I clear the P0043 code myself?

You can clear the code with an OBD-II scan tool, but if the underlying fault is still present it will usually return. Clearing without repair is only useful to confirm whether the fault is active.

Related codes

P0044

HO2S Heater Control Circuit High (Bank 1 Sensor 3)

P0045

Turbo/Super Charger Boost Control Solenoid Circuit/Open

P0042

HO2S Heater Control Circuit (Bank 1 Sensor 3)

P0046

Turbo/Super Charger Boost Control Solenoid Circuit Range/Performance

Important

This information is provided for general reference only. It is not repair advice and may not apply to every make or model. Manufacturer-specific codes can differ. Always confirm a diagnosis with a scan tool and, where needed, a qualified technician before replacing parts.