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P1164

HO2S11 Circuit Fault Bank 1 Sensor 1.

  • Acura
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
1
AreaFuel and air metering
64
FaultThe specific fault in that area

What it means

On Acura models, P1164 means the engine control unit has found a circuit fault with the Bank 1 Sensor 1 heated oxygen sensor (HO2S11), the upstream sensor fitted before the catalytic converter. The unit saw a signal or heater response from that sensor outside its expected range, so it cannot rely on the sensor for accurate fuel control. The exact test that sets the code can vary by model and engine, so check the manufacturer data for your car.

Symptoms

  • Check engine light on
  • Poor or uneven fuel economy
  • Rough or unstable idle
  • Hesitation or poor throttle response
  • Failed emissions test or high exhaust emissions

Possible causes

  • Failed or degraded upstream oxygen sensor (Bank 1 Sensor 1)likely
  • Damaged, chafed or corroded sensor wiring or connectorlikely
  • Exhaust leak near the sensor or upstream of it letting in false airpossible
  • Sensor contamination from oil, coolant or silicone, or from running rich for long periodspossible
  • Fuel delivery or air metering problem skewing the sensor readingspossible
  • Fault in the engine control unit sensor circuit or power or earth supplyrare

How to diagnose

  1. Read the stored codes and freeze frame data, noting engine temperature, load and fuel trim at the time the fault set, and check for any other codes.
  2. Visually inspect the Bank 1 Sensor 1 wiring and connector for heat damage, chafing, corrosion and a loose or damaged plug.
  3. Check the exhaust manifold and front pipe area for leaks or cracks upstream of the sensor.
  4. With a scan tool, watch live sensor voltage or air-fuel ratio data and the fuel trims to see whether the sensor responds correctly and whether the trims are within normal limits.
  5. Check the sensor heater circuit supply, earth and resistance against the manufacturer's specification for your model.
  6. Check the wiring between the sensor and the control unit for open circuits, short circuits and high resistance.
  7. Rule out underlying engine faults such as vacuum leaks, fuel pressure problems or misfires that could affect the sensor readings.
  8. Inspect the sensor tip for contamination and look for oil or coolant consumption as a source.

How to fix

  • Repair or replace damaged wiring, terminals or the connector.
  • Replace the Bank 1 Sensor 1 oxygen sensor with a correct part for the engine if it fails testing or is contaminated.
  • Repair any exhaust leaks near or ahead of the sensor.
  • Correct the underlying fuel, air or engine fault that caused contamination or abnormal readings.
  • Clear the code after repair and road test to confirm it does not return.

Can I keep driving?

Medium severity

The car can usually be driven short-term, but fuel control may be poor, which can raise fuel use and emissions and could stress the catalytic converter over time. Get it diagnosed soon, and stop driving if the engine runs badly.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

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