What the OBD-II code p0030 means

Fault code P0030 – a step-by-step guide to diagnosing and fixing it

The meaning of error code P0030 – HO2S Heater Control Circuit (Bank 1, Sensor 1)
P0030
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P0030: causes, symptoms and repairs

The meaning of fault code P0030

DTC P0030 indicates that the heater control circuit of oxygen sensor 1 on the first cylinder bank is malfunctioning. This heated device is located upstream of the car's cat converterand used to monitor the oxygen content in the exhaust. The engine control module (ECM) uses this information to achieve the ideal air-fuel ratio. The heater is supposed to warm the sensor up so that it can reach the operating temperature quickly, shortening the time it takes for the engine to enter a closed cycle.

Common causes of code P0030

  • Broken wires or short circuits. Electrical faults can occur when the insulation sheath is damaged or fraying.
  • Corroded electrical contacts. Corrosion is the result of exposure to dirt and moisture.
  • A loose or damaged connector, affecting the sensor signals. Over time, the connector wire can crack or break. Excessive vibration or rubbing can cause damage such as fretting corrosion.
  • A faulty heater. This may be due to permanent damage to the heater circuit or high resistance.
  • Using an oxygen sensor that does not comply with the vehicles specifications. This should be noticeable shortly after the component has been installed.
  • A bad ECM, generating false DTCs. This is a much less common problem.
Possible symptoms of this fault

  • The check engine light is activated
  • The engines power output is reduced
  • Fuel consumption may increase
  • You may experience jerking during acceleration
  • The sensor may be unresponsive or take longer to respond
  • As a result, the ECM will use a fixed fuel mixture
Recommended repairs

  • Check whether any other codes are present using a diagnostic scanner or application, such as an OBD2 scan tool. You should also take a look at the scan data, including the voltage readings. This will help you to quickly identify the cause of the fault.
  • First, conduct a visual inspection of the oxygen sensor body and components. If there are any visible signs of damage, replace the device. You will also need to inspect the wiring and connectors. If there are cracks in the cables or parts have melted or frayed, replace the components. You may need to remove rust from the connector contacts and apply an anti-corrosion treatmentto restore the connection. Only specialised products should be used for these components.
  • If the data from the scan indicates that 0 amps were detected from the O2 heater, it is highly likely that there is an open or short circuit. Disconnect the oxygen sensor connector and make sure the engine is off before measuring the voltage going through the B+ battery feed. This value should be 12 volts. If there is no reading, repair the short or open in the feed circuit and make sure to replace any blown car fuses. If the reading is normal, disconnect the ground circuit from the ECMs wiring connector and measure the resistance of the circuit. If the resistance is infinite, try to fix the short or open. If the values are within the normal range, the device itself is most likely defective.
Frequently Asked Questions (FAQ)

What does the code “P0030” mean?


It means that a problem has been detected with the upstream oxygen sensor on engine cylinder bank 1.

What causes it to appear?


It is normally the result of a short or open in the ground or power supply circuit, a damaged heater circuit or device, or an incompatible sensor.

How serious is this?


You should still be able to drive your car under these conditions. However, it is better to address the problem promptly to avoid high fuel consumption and regain engine stability.

Cars the fault code P0030 is most commonly found on

Fault code P0030 - HO2S Heater Control Circuit (Bank 1, Sensor 1) can occur with any car but is most often found on the following cars:

  • BMW: E90, E46
  • Subaru: Impreza, Forester, Legacy
  • VW: Polo, Golf
  • Mazda: 6, 3
  • Opel
  • Seat: Ibiza, Leon

If you get the code P0030 on your car, make sure that the diagnostics are carried out correctly and the error is still relevant. Check for symptoms associated with the problem and explore options for resolving it.

What to do if the fault code p 0030 appears

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