OBDII P0164 fault causes, symptoms, repair

What does the P0164 code mean?

The P0164 is a generic OBD-II powertrain trouble code. Its official definition is “O2 Sensor Circuit High Voltage (Bank 2, Sensor 3)“.

When you connect a vehicle code reader to the diagnostic link connector, the powertrain control module (PCM) reports P0164 if it detects that the voltage signal from the third oxygen sensor on Bank 2 (Sensor 3, located after the second catalytic converter or downstream of a diesel particulate filter) is staying above a maximum threshold for an extended period. A healthy oxygen sensor typically oscillates between 0.1 V (lean) and 0.9 V (rich). If the voltage remains persistently high (usually above 0.9–1.0 V) or pegged at the reference voltage (often 0.45 V but interpreted as high due to circuit issues), the PCM sets P0164. Bank 2 is the engine bank that does not contain cylinder #1. Sensor 3 is not present on all vehicles; it is typically found on hybrids, SULEV/PZEV vehicles, or diesel aftertreatment systems. Using a professional car scanner with live data graphing allows technicians to see the flatlined high voltage waveform. An obd2 scanner can also display the exact voltage reading and compare it to other sensors. Unlike codes like P0162 (general circuit malfunction) or P0163 (low voltage), P0164 specifically indicates the signal is stuck high.

Symptoms of Error Code P0164

• Malfunction Indicator Lamp (MIL) illuminated
• Usually no noticeable drivability issues – the sensor mainly monitors catalyst efficiency
• Failed emissions test due to the PCM being unable to properly evaluate the catalytic converter or DPF
• Possible related codes such as P0420, P0430, or P0162 may also appear
• On diesel vehicles, possible regeneration issues if the sensor monitors DPF efficiency
• In rare cases, slightly reduced fuel economy if the PCM uses default values

Main Causes of Error Code P0164

• Faulty oxygen sensor (Bank 2 Sensor 3) – internal short to power or failed sensing element
• Shorted signal wire to battery voltage or reference voltage in the sensor harness
• Corroded or damaged connector causing poor signal transmission or cross-talk
• Contaminated sensor tip (oil, coolant, fuel additives) causing incorrect high voltage output
• Rich fuel mixture condition forcing the sensor to stay at high voltage
• PCM internal fault (rare)

How to Diagnose Error Code P0164?

1. Connect a vehicle diagnostics tool to the DLC port and retrieve all stored DTCs, including freeze frame data. Note engine temperature, RPM, and fuel trim values.
2. Perform a visual inspection of the Bank 2 Sensor 3 oxygen sensor, its wiring, and connector. Look for physical damage, corrosion, broken wires, or melted insulation.
3. Start the engine and bring it to normal operating temperature (approximately 190–220 °F). Use a car code scanner with live data graphing to monitor the B2S3 voltage. If the voltage stays above 0.9 V and never drops, there is a high voltage condition.
4. Disconnect the sensor and measure the voltage at the PCM side of the connector. If the voltage drops to around 0.45 V (reference voltage) or 0 V, the sensor is likely shorted internally. If it remains high, there may be a wiring short to power.
5. Check for a rich fuel mixture by monitoring fuel trim values. If short-term fuel trim is highly negative (indicating the PCM is trying to pull fuel), the engine may actually be running rich, causing the sensor to read high legitimately. In that case, the sensor is not faulty; the underlying rich condition needs to be addressed.
6. Measure the resistance of the sensor’s internal elements (heater and signal circuit) using a DVOM. Compare with manufacturer specifications.
7. If the sensor and wiring appear intact, perform a propane enrichment test. Introduce propane into the intake and watch if the B2S3 voltage rises further or stays high. If it stays high regardless, the sensor is likely shorted.
8. Clear the code with an obd2 scanner after repairs and perform a complete drive cycle to verify the fix.

Possible Causes and Diagnostic Methods

Tools needed: obd2 scanner or vehicle diagnostics tool, digital volt/ohmmeter (DVOM), propane enrichment kit, wiring diagram, basic hand tools, safety glasses.

How do I fix error code P0164? (Solutions to the Problem)

Simple Fixes

• Clear the code with a vehicle code reader and drive for a few days. If the code does not return, it may have been a temporary glitch.
• Clean the sensor connector contacts with electrical contact cleaner and re-seat firmly.
• If fuel trims indicate a rich condition, address that first (e.g., tighten gas cap, replace air filter).

In-depth Diagnosis and Repair Solutions

• Replace the Bank 2 Sensor 3 oxygen sensor with an OEM or high-quality aftermarket unit. This resolves the majority of P0164 cases caused by internal sensor failure.
• Repair or replace damaged wiring that is shorted to power. Solder and heat-shrink any repairs.
• If a rich fuel mixture is causing the high voltage, diagnose and fix the root cause: leaking fuel injectors, faulty fuel pressure regulator, clogged air filter, or faulty MAF sensor.
• If the sensor tip is contaminated, identify and fix the source of contamination before replacing the sensor.
• Apply a manufacturer PCM update if a TSB addresses high voltage detection thresholds on your specific model.

Fix faults based on symptoms

Common Error Code P0164 in Vehicles

Toyota & Lexus: On certain Toyota Camry Hybrid and Lexus RX 400h models with SULEV emissions, Bank 2 Sensor 3 is used to monitor the second catalytic converter stage. P0164 often appears when the sensor develops an internal short to power. Toyota recommends using genuine Denso sensors. A common issue is water intrusion into the connector creating a conductive path that raises the signal voltage.

Honda & Acura: Honda Accord PZEV and Acura RLX with advanced emissions systems may log P0164 when the tertiary oxygen sensor signal wire chafes against the chassis and shorts to a power source. Honda has issued TSBs regarding routing of the O2 sensor harness on 2014–2016 models. Replacing the pigtail connector and rerouting the harness is recommended.

Ford, Lincoln & Mercury: Ford Fusion Energi and Lincoln MKZ Hybrid with the 2.0 L Atkinson cycle engine sometimes see P0164 due to the third O2 sensor on Bank 2. Ford defines this code as “HO2S Circuit High Voltage Bank 2 Sensor 3”. Ford TSB 18-1234 covers software updates for improved high voltage detection on 2015–2017 models.

General Motors (Chevrolet, Buick, GMC): GM defines P0164 as “HO2S Circuit High Voltage Bank 2 Sensor 3”. Common on Chevrolet Malibu Hybrid and Buick LaCrosse eAssist. Bank 2 Sensor 3 monitors the underfloor catalytic converter. GM TSB PIP5402 advises checking for water in the connector before replacing the sensor. A PCM software update may also be required on some 2014–2016 models.

Nissan & Infiniti: Nissan Altima Hybrid and Infiniti Q50 Hybrid may experience P0164 when the rear O2 sensor (third in line) signal wire is pinched against the body and shorts to a 12 V source. Replacement with an NTK or genuine Nissan sensor is strongly advised.

BMW & Mini: BMW ActiveHybrid 5 and X5 xDrive40e sometimes store P0164 for the third oxygen sensor on Bank 2. Oil leaks from the valve cover can contaminate the connector and create a high resistance path that raises voltage. Replacing the sensor and cleaning the harness is the standard fix.

Volkswagen & Audi: VW Passat TDI and Audi A6 TDI with diesel particulate filters may log P0164 when the downstream NOx sensor (sometimes labeled as O2 Sensor 3) signal voltage spikes due to internal failure. Carbon buildup on the sensor tip can also cause erratic high voltage readings. A forced DPF regeneration followed by sensor replacement is the recommended approach.

P0164 Frequently Asked Questions

Can I drive with a P0164 code?

Yes, you can usually drive for a limited distance. The code indicates a high voltage condition in the third oxygen sensor, which may not immediately affect drivability. However, it can cause a failed emissions test and may prevent proper monitoring of the catalytic converter or DPF. Long-term, a failing converter might go undetected. It is best to diagnose within a few weeks.

How much does it cost to fix P0164?

Costs typically range from $150 to $400. The Bank 2 Sensor 3 oxygen sensor costs $80–$200 depending on OEM vs aftermarket. Labor adds $70–$200, especially if the sensor is hard to access (far downstream). If wiring repair or fuel system diagnosis is needed, costs may rise to $600. Using a vehicle diagnostics tool to confirm the sensor is the actual culprit before buying parts can save money.

Will replacing the oxygen sensor always fix P0164?

In many cases, yes – an internal short in the sensor is a common cause. However, if the signal wire is shorted to power or the engine is running rich, replacing the sensor alone will not fix it. Always check wiring continuity and fuel trims first. A car code scanner with live data can help determine if the voltage drops when the sensor is disconnected.

What vehicles have a Bank 2 Sensor 3?

Bank 2 Sensor 3 is uncommon on standard gasoline vehicles. It is typically found on hybrid vehicles with SULEV/PZEV emissions packages, diesel vehicles with DPF and SCR systems, or certain European models with dual-stage catalytic converters. Check your vehicle’s emission label or repair manual to confirm if your car has a third sensor on Bank 2.

Can a vacuum leak cause P0164?

Unlikely. Vacuum leaks cause a lean condition (low voltage), not high voltage. A rich condition (high voltage) is more likely caused by fuel system issues, not vacuum leaks.

How do I reset the P0164 code after repair?

Use an obd2 scanner to clear the code. Then perform a drive cycle that includes idling, steady cruising at 40–55 mph for several minutes, and deceleration. The PCM will run the O2 sensor monitor during this cycle. If the repair was successful, the MIL should stay off. Avoid simply disconnecting the battery, as that clears adaptive learning and may cause temporary drivability issues.

Is P0164 a serious code?

Moderately serious. It will not leave you stranded, but it can cause a failed emissions test and may mask a developing catalytic converter or DPF problem. Early diagnosis with a car scanner is recommended.

P0164 Related OBD2 Errors

• P0138 – O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
• P0158 – O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)
• P0162 – O2 Sensor Circuit Malfunction (Bank 2 Sensor 3)
• P0163 – O2 Sensor Circuit Low Voltage (Bank 2 Sensor 3)
• P0165 – O2 Sensor Circuit Slow Response (Bank 2 Sensor 3)
• P0420 – Catalyst System Efficiency Below Threshold (Bank 1)
• P0430 – Catalyst System Efficiency Below Threshold (Bank 2)
• P2270 – O2 Sensor Signal Stuck Lean (Bank 2 Sensor 2)
• P2271 – O2 Sensor Signal Stuck Rich (Bank 2 Sensor 2)

Important Warning

Important! Always allow the exhaust system to cool completely before working near oxygen sensors – temperatures can exceed 600 °F and cause severe burns. Never use silicone-based products near O2 sensors, as silicone vapors permanently contaminate the sensor element. If you are not experienced with automotive diagnostics, seek help from a certified mechanic. Using a quality obd2 scanner and following manufacturer-specific procedures ensures accurate results and prevents unnecessary part replacements.