Understanding trouble code P0152

Learn what trouble code P0152 means and how to fix it

Trouble code P0152 is defined as: Oxygen Sensor Circuit High Voltage (Bank 2 Sensor 1). Bank 2 is the bank that doesn’t house cylinder #1 and sensor 1 is before the catalytic converter. Trouble code P0152 is a fairly common code. And like all trouble codes, just because the sensor’s name is part of the description, that DOESN’T automatically mean the sensor is bad. In fact, the sensor could be telling the truth and the real problem might be, and often is, a vacuum leak or a leaking fuel injector. So, do your testing before you automatically throw in a new oxygen sensor.

What trouble code P0152 means

An oxygen sensor submits a high voltage when it sees a lack of oxygen in the exhaust stream. That’s the symptom of an overly rich mixture. When the ECM sees a consistently high rich mixture for longer than a set period of time, it sets this trouble code

What are the most common causes of a trouble code P0152

• Leaking fuel injectors
• Excessive fuel pressure due to a faulty fuel pressure regulator
• Wiring issue — sensor signal is shorted to voltage

Inspect the Oxygen Sensor
• Check the wiring and connections leading to the oxygen sensor. Ensure there are no breaks, corrosion, or loose connections.
• Visually inspect the sensor itself for any damage or contamination. Replace the sensor if it appears damaged or has exceeded its service life.

Test the Oxygen Sensor
• Use a scan tool to monitor the oxygen sensor’s voltage output in real-time. Check if the sensor is responding correctly to changes in the air-fuel mixture.
• Perform a voltage check to verify if the sensor is within the specified range. A malfunctioning sensor may need replacement.

Check for Exhaust Leaks
• Exhaust leaks near the oxygen sensor can cause incorrect readings. Inspect the exhaust system for leaks, especially around the sensor location. Repair any leaks found.

Most pros check sensor operation with a scan tool. But there are some checks you can perform with a digital voltmeter. For example, you can connect a DVOM multimeter in series with the sensor’s voltage reference line (refer to a wiring diagram for the proper connection). Connect the black negative lead to the sensor end of the reference wire, and the red positive lead to the PCM end of the wire. The meter should then show an increase in voltage (above the reference voltage) if the air/fuel mixture is lean, or a drop in voltage (below the reference voltage) if the mixture is rich.

Be aware:

Honda’s 5-wire “Lean Air Fuel” (LAF) sensor contains a special calibration
Resistor in the connector. If the connector is damaged or contaminated with oil the resistance value will be off.

If an O2 sensor, wideband O2 sensor or A/F sensor fails due to coolant contamination, do not replace the sensor until you repair the root cause, or the new sensor will suffer the same fate.

© 2012 Rick Muscoplat