Code P0058: High HO2S Heater Control Circuit (Bank 2, Sensor 2)
The generic diagnostic trouble code P0058 indicates a problem with abnormally high voltage in the heater control circuit of the Heated Oxygen Sensor (HO2S) located at Bank 2, Sensor 2. This code belongs to the generic Powertrain code family (OBD-II) and applies to most vehicles from 1996 to the present.
Role of the HO2S and its Heater
Heated Oxygen Sensors (HO2S) are essential components of the engine management system. The Powertrain Control Module (PCM) uses their signals to analyze the oxygen content in the exhaust gases and, for the Sensor 2 of each bank, primarily to monitor the efficiency of the catalytic converter.
The integrated heater element allows the sensor to quickly reach its optimal operating temperature (around 600°C), thereby reducing the time to reach “closed loop” operation and improving engine efficiency and emission control right from startup.
Heater Circuit Operation
There are two main configurations for controlling the oxygen sensor’s heater element:
- Power Side Control (+12V): The PCM directly controls the power supply (via a relay or not), while the ground is connected to a chassis ground.
- Ground Side Control (GND): A fused +12V supply (B+) is provided continuously when the ignition is on. The PCM then controls the circuit by acting on the ground side of the heater element.
The P0058 code triggers when the PCM detects an abnormally high voltage condition on the control circuit for this heater element. Bank 2 refers to the side of the engine that does not contain cylinder number 1.
Symptoms of Code P0058
- Illumination of the Malfunction Indicator Lamp (MIL) on the dashboard.
- Frequent absence of other visible symptoms or driving issues.
- In some cases, an increase in pollutant emissions or a slight change in fuel consumption.
Probable Causes
Several malfunctions can cause the P0058 code:
- Faulty HO2S: Internal heater element shorted.
- Wiring Problem: Short to battery voltage (B+) in the control circuit (for PCM-controlled systems).
- Wiring Problem: Short to ground on the control circuit (for systems where the PCM controls the ground).
- Electrical Connection: Bad connector, corrosion, or exposed wire.
- PCM Failure (rare): An internal problem within the engine control module.
Diagnosis and Possible Solutions
⚠️ Warning: This advice is for informational purposes. For an accurate diagnosis, using an OBD2 scanner and a multimeter is highly recommended. Consult the specific procedures for your vehicle.
- Visual Inspection: Start by carefully inspecting the Bank 2 Sensor 2, its connector, and its wiring harness. Look for signs of physical damage, burning, or chafed/melted wires (especially near the exhaust). Check the condition of the wires at the sensor entry point, a common fatigue point.
- Electrical Test:
- Disconnect the HO2S sensor connector.
- Depending on the system type (power or ground controlled), check for the presence of expected voltages (e.g., +12V with ignition on) and the integrity of the circuits using a multimeter.
- Measure the resistance of the sensor’s heater element (consult the manufacturer’s specifications). An infinite resistance (open circuit) or zero resistance (short circuit) confirms a faulty sensor.
- Replacement: If the wiring and connections are intact but the sensor tests faulty, its replacement is the most likely solution. Use an OEM quality or equivalent sensor.
- Clearing the Code: After repair, clear the trouble code with an OBD2 scanner and perform a drive cycle to verify that it does not reappear.
Call to Action
The P0058 code indicates an electrical problem that can, over time, damage the PCM. Although the vehicle may seem to operate normally, it is crucial to diagnose and repair the fault to ensure the proper functioning of the anti-pollution system and avoid potential future problems. If you are not comfortable with these procedures, consult a professional mechanic for an expert diagnosis.