P0143

Severity: Low

O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3)

Last updated: July 2026

System

Powertrain

Subsystem

Fuel & Air Metering

Code Type

Generic (SAE)

What does P0143 mean?

P0143 is a generic (SAE) powertrain diagnostic trouble code. It is defined as "O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3)". It falls under the fuel & air metering area of the vehicle’s powertrain system, and has the same core meaning across most makes and models.

When is P0143 set?

The onboard diagnostic system sets P0143 when it detects a condition matching "o2 sensor circuit low voltage (bank 1 sensor 3)" in the fuel & air metering 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 P0143 code mean?

P0143 means "O2 Sensor Circuit Low Voltage (Bank 1 Sensor 3)". It is a generic powertrain trouble code in the fuel & air metering area.

Is it safe to drive with a P0143 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 P0143 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 P0143 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

P0144

O2 Sensor Circuit High Voltage (Bank 1 Sensor 3)

P0145

O2 Sensor Circuit Slow Response (Bank 1 Sensor 3)

P0142

O2 Sensor Circuit Malfunction (Bank 1 Sensor 3)

P0146

O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 3)

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.