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P0164 Code Explained: O2 Sensor Circuit High Voltage (Bank 2 Sensor 3) Causes, Symptoms & Fixes

P0164 code illustration showing the Bank 2 Sensor 3 oxygen sensor with a high-voltage warning, secondary catalytic converter, Check Engine Light, Pro Street TV logo, and www.ProStreetOnline.com.

If your OBD-II scanner displays P0164, your vehicle’s Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected that the Bank 2 Sensor 3 oxygen (O2) sensor voltage has remained above the manufacturer’s expected operating range for longer than allowed.

The generic OBD-II definition for P0164 is:

O2 Sensor Circuit High Voltage (Bank 2 Sensor 3)

Bank 2 Sensor 3 is the third oxygen sensor located on the engine bank that does not contain cylinder number one. On vehicles equipped with multiple catalytic converters, this sensor is typically installed after the secondary catalytic converter and is responsible for monitoring long-term catalyst efficiency and emissions performance.

Unlike upstream oxygen sensors that continuously adjust the air-fuel mixture, Bank 2 Sensor 3 is used primarily for emissions monitoring and catalyst verification.

The PCM relies on Bank 2 Sensor 3 to monitor:

When the PCM detects that the Bank 2 Sensor 3 voltage remains consistently higher than the programmed threshold, it stores P0164 and usually illuminates the Check Engine Light.

Common causes include:

Unlike P0163, which indicates a low-voltage condition, P0164 indicates that the oxygen sensor voltage remains abnormally high.

What Does the P0164 Code Mean?

A zirconia oxygen sensor generates its own voltage by comparing oxygen levels inside the exhaust to outside air.

Normally, a downstream oxygen sensor produces a relatively stable voltage signal after the catalytic converter.

When the PCM continuously detects higher-than-expected voltage, it interprets the condition as either:

The code does not automatically mean the engine is running rich.

Where Is Bank 2 Sensor 3 Located?

Bank 2 Sensor 3 is mounted after the secondary catalytic converter on the cylinder bank opposite cylinder number one.

On vehicles equipped with three oxygen sensors per bank:

Many vehicles do not use a third oxygen sensor, making P0164 less common than earlier oxygen sensor codes.

Bank 2 Sensor 1 vs. Sensor 2 vs. Sensor 3

Understanding sensor locations simplifies diagnosis.

Bank 2 Sensor 1

Located before the catalytic converter.

Responsible for:

Bank 2 Sensor 2

Located after the primary catalytic converter.

Responsible for:

Bank 2 Sensor 3

Located after the secondary catalytic converter.

Responsible for:

Because Sensor 3 is dedicated to emissions monitoring, P0164 usually produces little or no noticeable drivability problems.

How the Bank 2 Sensor 3 Oxygen Sensor Works

The downstream oxygen sensor measures oxygen remaining after exhaust gases pass through the secondary catalytic converter.

The PCM compares information from:

to evaluate overall catalytic converter efficiency.

If Sensor 3 continuously reports a voltage higher than expected, the PCM stores P0164.

What Does “High Voltage” Mean?

High voltage means the oxygen sensor signal remains above the manufacturer’s expected operating range.

Possible causes include:

The high-voltage condition may result from an actual exhaust-related issue or an electrical fault within the sensor circuit.

How the PCM Detects P0164

The PCM continuously monitors:

If Bank 2 Sensor 3 remains above the programmed voltage threshold for a specified period, the PCM stores P0164.

Most manufacturers require multiple failed drive cycles before permanently illuminating the Check Engine Light.

Why Bank 2 Sensor 3 Is Important

Although Sensor 3 does not directly control fuel delivery, it plays an important role in emissions compliance.

It helps the PCM evaluate:

Without accurate Sensor 3 data, the PCM cannot properly verify secondary catalyst efficiency.

Can a Bad Oxygen Sensor Cause P0164?

Yes.

A deteriorated Bank 2 Sensor 3 oxygen sensor is one of the most common causes of P0164.

Typical failures include:

As oxygen sensors age, they may begin producing inaccurate voltage signals that remain consistently high.

Can Wiring Problems Cause P0164?

Absolutely.

Electrical faults frequently trigger P0164.

Common wiring issues include:

Because Sensor 3 is located near the exhaust system, the wiring harness is frequently exposed to high temperatures.

P0164 Quick Facts

ItemInformation
DTCP0164
Generic DefinitionO2 Sensor Circuit High Voltage (Bank 2 Sensor 3)
SystemFuel & Emissions
Sensor LocationBank 2 Sensor 3
SeverityLow to Moderate
Safe to Drive?Yes (Usually)
Common SymptomsCheck Engine Light, failed emissions inspection, incomplete readiness monitors
Common CausesFailed oxygen sensor, wiring short, connector corrosion, rich exhaust condition
Typical Repair Cost$100–700+
Related CodesP0162, P0163, P0165, P0166, P0167

Common Vehicles That Experience P0164

P0164 is commonly found on certain:

Vehicles equipped with three oxygen sensors per cylinder bank are the most likely to store this diagnostic trouble code.

What Does P0164 Really Mean?

The wording of P0164 often causes drivers to assume the engine is running rich.

The code does not automatically mean:

Instead, it means the PCM has detected that the Bank 2 Sensor 3 oxygen sensor voltage remains higher than expected, preventing accurate secondary catalyst monitoring.

The problem may involve:

Think of P0164 as the PCM saying:

“The third oxygen sensor on Bank 2 is producing a voltage signal that’s higher than expected. I need the sensor and its electrical circuit inspected before I can accurately monitor secondary catalytic converter performance.”

Common P0164 Scan Tool Patterns

Monitoring live scan-tool data is one of the fastest ways to diagnose P0164.

Unlike P0163, which indicates the Bank 2 Sensor 3 oxygen sensor voltage is too low, P0164 indicates the sensor voltage remains consistently higher than the manufacturer’s expected operating range.

Professional scan tools allow technicians to monitor oxygen sensor voltage, signal stability, catalyst monitor operation, fuel system behavior, and electrical performance to determine whether the high-voltage condition is caused by a failed oxygen sensor, wiring fault, rich-running engine, or PCM issue.

Pattern 1: Sensor Voltage Remains High

The most common scan-tool pattern is:

Possible causes include:

Pattern 2: Other Oxygen Sensors Operate Normally

Compare:

If:

The fault is usually isolated to the Bank 2 Sensor 3 circuit.

Comparing sensor data helps eliminate engine fuel-control issues.

Pattern 3: Secondary Catalyst Monitor Cannot Complete

Monitor:

Common observations include:

Without accurate Sensor 3 voltage data, the PCM cannot properly evaluate secondary catalytic converter efficiency.

Pattern 4: Voltage Changes When Harness Is Moved

While monitoring live data:

If voltage suddenly changes, suspect:

Harness movement testing is useful for locating hidden wiring problems.

Pattern 5: High Voltage After Full Warm-Up

Some vehicles only store P0164:

This often indicates:

Pattern 6: Heater Operates Normally but Voltage Stays High

Some scan tools show:

Possible causes include:

A properly functioning heater does not guarantee an accurate oxygen sensor signal.

Common Symptoms of P0164

Because Bank 2 Sensor 3 primarily monitors emissions, drivability symptoms are generally minimal.

Common symptoms include:

Many drivers notice no symptoms other than the illuminated Check Engine Light.

Check Engine Light

The Check Engine Light is usually the first symptom.

Most manufacturers require:

before storing P0164.

Failed Emissions Inspection

P0164 commonly causes emissions failures because:

Even if the vehicle drives normally, it will usually fail an emissions inspection.

Increased Exhaust Emissions

Without accurate Bank 2 Sensor 3 data:

Slight Fuel Economy Changes

Although uncommon, some vehicles may experience:

Since Sensor 3 does not directly control fuel delivery, these changes are generally very small.

Is P0164 Serious?

P0164 is generally considered a low-to-moderate severity diagnostic trouble code.

Most vehicles remain safe to drive.

However, delaying repairs may eventually result in:

Repairs should be completed before emissions testing.

Can You Drive With P0164?

Yes.

Driving is generally safe if:

Repairs should be scheduled promptly if:

P0164 vs Related Trouble Codes

Understanding related Bank 2 Sensor 3 codes simplifies diagnosis.

P0162

O2 Sensor Circuit Malfunction (Bank 2 Sensor 3)

General electrical fault affecting the oxygen sensor circuit.

P0163

O2 Sensor Circuit Low Voltage (Bank 2 Sensor 3)

The oxygen sensor voltage remains below manufacturer specifications.

P0164

O2 Sensor Circuit High Voltage (Bank 2 Sensor 3)

The oxygen sensor voltage remains above manufacturer specifications.

P0165

O2 Sensor Circuit Slow Response (Bank 2 Sensor 3)

The oxygen sensor reacts slower than expected.

P0166

O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 3)

The PCM detects no usable oxygen sensor signal.

P0167

O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 3)

Electrical fault affecting the oxygen sensor heater circuit.

30 Common Causes of P0164

The most common causes include:

  1. Failed Bank 2 Sensor 3 oxygen sensor
  2. Short to battery voltage
  3. Shorted signal wire
  4. Rich-running engine
  5. Broken wiring harness
  6. Connector corrosion
  7. Loose electrical connector
  8. Melted wiring near the exhaust
  9. Poor ground connection
  10. Internal sensor failure
  11. Carbon contamination
  12. Oil contamination
  13. Coolant contamination
  14. Moisture intrusion
  15. Heat damage
  16. Rodent damage
  17. Previous wiring repairs
  18. Incorrect replacement sensor
  19. Damaged PCM connector
  20. Charging system voltage problems
  21. Fuel injector leakage
  22. Excessive fuel pressure
  23. Wiring short to power
  24. High circuit voltage
  25. Electrical interference
  26. Internal connector damage
  27. PCM software issue
  28. Internal PCM driver fault
  29. Harness routing damage
  30. PCM failure (rare)

Final Thoughts

The P0164 O2 Sensor Circuit High Voltage (Bank 2 Sensor 3) code indicates the PCM has detected that the third oxygen sensor on Bank 2 is consistently producing a voltage signal higher than expected. While a deteriorated oxygen sensor is one of the most common causes, shorted wiring, rich-running engine conditions, connector corrosion, poor grounds, electrical faults, and power supply problems can all produce the same high-voltage condition.

Proper diagnosis should determine whether the fault originates in:

The next section of this guide covers:

Following a structured diagnostic process prevents unnecessary oxygen sensor replacement while restoring accurate secondary catalyst monitoring and proper OBD-II readiness.

Related Pro Street Diagnostic Guides

How to Diagnose the P0164 Code

Diagnosing P0164 requires determining why the Bank 2 Sensor 3 oxygen sensor is producing a voltage signal that remains higher than the manufacturer’s expected operating range.

Unlike P0163, which indicates a consistently low-voltage signal, P0164 specifically indicates the oxygen sensor voltage remains abnormally high.

The high-voltage condition may be caused by:

Proper diagnosis should determine whether the problem originates in the oxygen sensor, electrical circuit, engine operation, or PCM before replacing expensive components.

Safety Precautions

Before beginning diagnosis:

Bank 2 Sensor 3 is typically mounted near the secondary catalytic converter where temperatures frequently exceed 800°F (425°C).

Tools Required

Professional diagnosis may require:

An oscilloscope provides the most accurate method for evaluating oxygen sensor voltage waveforms.

Step 1 – Verify the Code

Connect a professional scan tool.

Record:

Monitor:

Always save freeze-frame information before clearing diagnostic trouble codes.

Step 2 – Check for Related Trouble Codes

P0164 commonly appears with:

Related codes often simplify diagnosis.

Code CombinationLikely Diagnosis
P0164 onlyHigh-voltage sensor fault
P0164 + P0162Electrical circuit problem
P0164 + P0175Rich-running engine
P0164 + P0167Heater circuit concern
Multiple oxygen sensor codesWiring or PCM issue

Repair related faults before replacing major components.

Step 3 – Monitor Live Oxygen Sensor Data

Allow the engine to reach operating temperature.

Observe:

Normal operation:

Abnormal operation:

These conditions indicate additional testing is necessary.

Step 4 – Compare Other Oxygen Sensors

Compare:

If:

The fault is usually isolated to Bank 2 Sensor 3 or its circuit.

Comparing all oxygen sensors helps eliminate broader engine management problems.

Step 5 – Inspect the Oxygen Sensor

Inspect Bank 2 Sensor 3 for:

A damaged sensing element may continuously report an abnormally rich exhaust condition.

Step 6 – Inspect the Electrical Connector

Disconnect the oxygen sensor connector.

Inspect for:

Connector faults can create false high-voltage readings.

Step 7 – Inspect the Wiring Harness

Inspect wiring between the oxygen sensor and PCM.

Look for:

Signal wires shorted to battery voltage commonly trigger P0164.

Step 8 – Test Signal Circuit Continuity

Using a digital multimeter:

Measure continuity between:

Inspect for:

Repair wiring faults before replacing the oxygen sensor.

Step 9 – Verify Ground Integrity

Inspect the oxygen sensor ground circuit.

Measure:

Inspect for:

Poor ground connections can artificially elevate oxygen sensor voltage.

Step 10 – Check for Rich Engine Operation

Although Bank 2 Sensor 3 does not control fuel delivery, verify the engine is not operating excessively rich.

Inspect:

An actual rich-running engine may contribute to consistently high downstream oxygen sensor voltage.

Step 11 – Measure Circuit Voltage

Using a multimeter:

Measure:

Look for:

Voltage measurements help identify circuit faults.

Step 12 – Evaluate Secondary Catalyst Performance

Monitor:

If Sensor 2 behaves normally while Sensor 3 remains high, the fault is usually isolated to Sensor 3 or its electrical circuit.

Step 13 – Review Technical Service Bulletins

Before replacing expensive components:

Review manufacturer Technical Service Bulletins (TSBs).

Look for updates involving:

Software updates occasionally resolve false high-voltage codes.

Step 14 – Review Freeze-Frame Data

Compare current operating conditions with stored freeze-frame information.

Review:

Freeze-frame information often identifies the operating conditions that triggered P0164.

Step 15 – Inspect PCM Connector Integrity

Inspect PCM connectors for:

Poor PCM connections may interrupt accurate oxygen sensor communication.

Step 16 – Test the Oxygen Sensor Using an Oscilloscope

An oscilloscope provides the most accurate diagnosis.

Evaluate:

A consistently high waveform confirms the high-voltage condition.

Step 17 – Verify Charging System Voltage

Measure charging voltage.

Normal charging voltage should remain between:

Charging system abnormalities can contribute to unstable sensor signals.

Step 18 – Confirm Sensor Power Supply

Verify:

Improper electrical supply can contribute to abnormal sensor voltage.

Step 19 – Inspect Previous Repairs

Inspect for:

Improper repairs frequently create intermittent high-voltage conditions.

Step 20 – Confirm the Diagnosis

Before replacing any major component, verify:

Completing these diagnostic steps prevents unnecessary oxygen sensor replacement while accurately identifying the root cause of P0164.

Next Section

Part 2B covers:

Step 21 – Replace the Bank 2 Sensor 3 Oxygen Sensor

If testing confirms the Bank 2 Sensor 3 oxygen sensor has failed internally and is consistently producing an abnormally high voltage signal, replacement is the proper repair.

General replacement procedure:

  1. Allow the exhaust system to cool completely.
  2. Disconnect the oxygen sensor electrical connector.
  3. Remove the sensor using an oxygen sensor socket.
  4. Inspect the sensor threads and catalytic converter bung.
  5. Install an OEM or high-quality replacement oxygen sensor.
  6. Tighten the sensor to the manufacturer’s specified torque.
  7. Reconnect the electrical connector.
  8. Clear all diagnostic trouble codes.
  9. Verify proper sensor operation using a professional scan tool.

OEM oxygen sensors generally provide more accurate voltage readings, longer service life, and better compatibility with the vehicle’s emissions system.

Step 22 – Repair Shorted Wiring

Inspect the complete Bank 2 Sensor 3 wiring harness.

Repair:

Short circuits are one of the most common electrical causes of P0164.

Step 23 – Repair Connector Problems

Inspect the oxygen sensor connector.

Repair or replace:

Poor electrical connections can create false high-voltage signals.

Step 24 – Repair Ground Circuit Problems

Inspect:

Measure:

Poor grounds frequently cause inaccurate oxygen sensor voltage readings.

Step 25 – Repair Rich Engine Conditions

Although Sensor 3 does not control fuel delivery, excessive fuel can produce a genuine high-voltage oxygen sensor signal.

Inspect and repair:

Correct engine performance problems before replacing emissions components.

Step 26 – Repair High Circuit Voltage

Measure the sensor circuit for excessive voltage.

Inspect:

Repair abnormal voltage conditions before replacing expensive components.

Step 27 – Repair Charging System Problems

High charging voltage can interfere with oxygen sensor operation.

Inspect:

Normal charging voltage should remain between:

Correct charging system faults before continuing diagnosis.

Step 28 – Update PCM Software

Before replacing the PCM:

Review manufacturer Technical Service Bulletins (TSBs).

Manufacturers occasionally release PCM software updates addressing:

Always verify the PCM contains the latest available software calibration.

Step 29 – Verify Oxygen Sensor Operation

After repairs:

Monitor:

A properly functioning downstream oxygen sensor should provide a stable voltage signal that allows the PCM to accurately verify secondary catalytic converter efficiency.

Step 30 – Consider PCM Failure

PCM failure is extremely uncommon.

Only suspect the PCM after confirming:

PCM replacement should always be the final diagnostic step.

How to Fix P0164

The proper repair depends entirely on the diagnostic results.

Common repairs include:

Verifying the Repair

After completing repairs:

  1. Clear all diagnostic trouble codes.
  2. Start the engine.
  3. Allow the engine to reach operating temperature.
  4. Monitor Bank 2 Sensor 3 voltage.
  5. Verify stable downstream oxygen sensor activity.
  6. Complete a full drive cycle.
  7. Confirm oxygen sensor and catalyst readiness monitors complete.
  8. Verify no pending or permanent DTCs return.
  9. Perform a final scan to confirm the repair.

A successful repair restores accurate secondary catalyst monitoring, completes emissions readiness monitors, and eliminates the high-voltage condition.

Typical Repair Costs

RepairTypical Cost
Professional diagnosis$100–250
Bank 2 Sensor 3 replacement$175–500
Wiring repair$100–400
Short circuit repair$100–400
Connector replacement$100–300
Ground circuit repair$100–250
Fuel system diagnosis/repair$150–800
Battery replacement$150–350
Alternator replacement$400–1,000
PCM software update$100–250
PCM replacement$800–2,000+

Repair costs vary depending on vehicle design, labor rates, oxygen sensor accessibility, and the underlying cause of the high-voltage condition.

Common Diagnostic Mistakes

Avoid these common mistakes:

Many P0164 repairs involve correcting electrical or fuel system problems rather than replacing the oxygen sensor.

Manufacturer-Specific Notes

Ford

Inspect:

Heat-damaged wiring commonly contributes to P0164 on Ford vehicles.

General Motors (Chevrolet/GMC)

Verify:

Electrical shorts and poor grounds are common causes on GM applications.

Toyota/Lexus

Inspect:

Toyota factory scan tools provide enhanced downstream oxygen sensor diagnostics.

Honda/Acura

Inspect:

Connector corrosion and damaged wiring commonly create false high-voltage signals.

Nissan/Infiniti

Verify:

High exhaust temperatures frequently damage downstream sensor wiring.

BMW/Mercedes-Benz

Inspect:

Factory diagnostic software provides detailed oxygen sensor circuit analysis.

Hyundai/Kia

Inspect:

Electrical connector problems are common causes of P0164.

Frequently Asked Questions

What usually fixes P0164?

The most common repairs include replacing the Bank 2 Sensor 3 oxygen sensor, repairing shorted wiring, correcting rich-running engine conditions, replacing damaged connectors, repairing poor grounds, or updating PCM software.

Can I drive with P0164?

Yes. Most vehicles remain drivable, but repairs should be completed before emissions testing because P0164 commonly prevents secondary catalyst readiness monitors from completing.

Does P0164 always mean the oxygen sensor is bad?

No. Shorted wiring, rich-running engine conditions, connector corrosion, poor grounds, and electrical faults can all trigger P0164 without the oxygen sensor itself being defective.

Can a rich-running engine cause P0164?

Yes. An excessively rich air-fuel mixture can cause the downstream oxygen sensor to produce a consistently high voltage signal, resulting in a P0164 code.

Can P0164 cause a failed emissions inspection?

Yes. Because Bank 2 Sensor 3 monitors secondary catalyst efficiency, P0164 commonly prevents OBD-II readiness monitors from completing and usually results in an emissions inspection failure.

Is P0164 a serious code?

P0164 is generally considered a low-to-moderate severity diagnostic trouble code. While it rarely affects drivability, it can increase emissions, interrupt secondary catalyst monitoring, and prevent emissions compliance if left unrepaired.

Final Thoughts

The P0164 O2 Sensor Circuit High Voltage (Bank 2 Sensor 3) code indicates the PCM has detected that the third oxygen sensor on Bank 2 is consistently producing a voltage signal higher than expected. While a deteriorated oxygen sensor is a common cause, shorted wiring, rich-running engine conditions, connector corrosion, poor grounds, excessive circuit voltage, and electrical faults can all produce the same high-voltage condition.

A complete diagnosis should always verify:

Following a structured diagnostic process prevents unnecessary parts replacement while restoring accurate secondary catalyst monitoring, emissions compliance, and complete OBD-II readiness.

Continue Your Pro Street Bank 2 Sensor 3 Series

Related guides include:

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