AutoFixDB - Free OBD-II diagnostic trouble code lookup. Find causes, symptoms, diagnostic steps and repair solutions.

Overview

P0163 indicates low voltage detected in the oxygen sensor circuit for Bank 2 Sensor 3, often pointing to wiring issues, sensor failure, or exhaust leaks impacting emissions monitoring.

Common Symptoms

Check Engine Light (MIL) illuminated
Reduced fuel efficiency
Possible rough idle or hesitation
Potential failed emissions test

Most Common Causes

Faulty Bank 2 Sensor 3 oxygen sensor high

Post‑catalyst O2 sensor degradation often leads to low voltage signal outputs below the PCM threshold.

Damaged or corroded wiring/connectors in the O2 sensor circuit high

Open circuits, shorts to ground, or poor connections skew sensor voltage readings.

Exhaust leaks upstream of Bank 2 Sensor 3 medium

Air intrusion alters exhaust composition and leads to low sensor voltage indications.

PCM/ECM sensor circuit driver fault low

Rare failure of module processing can misreport normal voltages as low.

Diagnostic Steps

Verify DTC and monitor live O2 sensor voltages with a scan tool

Expected: Bank 2 Sensor 3 voltage should fluctuate within normal range (~0.1â€“0.9V at operating temp)

Interpretation: Consistent low voltage confirms circuit or sensor issue
Visually inspect sensor harness and connector for damage or corrosion

Expected: No breaks, corrosion, or loose pins

Interpretation: Damage indicates wiring repair before further testing
Check for exhaust leaks upstream of the sensor

Expected: No leaks detected

Interpretation: Leaks can introduce false air, leading to low readings
Measure reference voltage and ground at sensor connector with multimeter

Expected: Proper reference voltage and solid ground

Interpretation: Absence indicates wiring harness or PCM issues
Replace sensor if wiring and power checks are within specifications

Expected: Resolved low voltage signal and cleared fault

Interpretation: Bad sensor was cause

Repair Solutions

Replace Bank 2 Sensor 3 oxygen sensor medium

Estimated Cost: $100 - $300

Most frequent and effective repair when sensor output is consistently low

Repair or replace damaged wiring/connectors medium

Estimated Cost: $50 - $200

Cost varies with extent of wiring issues

Repair exhaust leaks upstream of sensor medium

Estimated Cost: $100 - $400

Necessary if leaks are contributing to incorrect sensor readings

PCM/ECM replacement or reprogramming hard

Estimated Cost: $500 - $1200

Considered only after all other root causes are ruled out

Common Misdiagnoses

Avoid these common diagnostic mistakes:

Replacing the wrong oxygen sensor (confusing bank and sensor number)

Frequently Asked Questions

What is the definition of the P0163 engine code?

Technically, the P0163 code represents O2 Sensor Circuit Low Voltage (Bank 2, Sensor 3). It usually points to a fault within the Emissions.

How serious is the P0163 code?

The P0163 code is considered medium severity. MIL/Check Engine illumination; generally minimal direct drivability impact but may affect emissions and fuel economy

How do I know if I have code P0163?

Common symptoms include: Check Engine Light (MIL) illuminated, Reduced fuel efficiency, Possible rough idle or hesitation. You might also notice the Check Engine Light is on.

What parts fail when P0163 is set?

The most common causes are: Faulty Bank 2 Sensor 3 oxygen sensor, Damaged or corroded wiring/connectors in the O2 sensor circuit, Exhaust leaks upstream of Bank 2 Sensor 3.

What is the price difference for fixing P0163?

Expect to pay around $200 if the issue is a Repair or replace damaged wiring/connectors, but up to $1200 if the PCM/ECM replacement or reprogramming needs replacement.

Does P0163 affect Ford, Toyota, or Honda?

Yes, P0163 is a generic code that applies to all OBD-II compliant vehicles, including Ford, Toyota, Honda, Chevrolet, Nissan, Dodge, BMW, and more.

P0163: O2 Sensor Circuit Low Voltage (Bank 2, Sensor 3)