2003 Mercury Grand Marquis OBD2 Code P0052 HO2S Heater Control Circuit High (Bank 2 Sensor 1)

P0052 code definition

HO2S Heater Control Circuit High (Bank 2 Sensor 1)

What the P0052 code means

This code is seen when the Engine Control Module (ECM) tries to control the heater control circuit for Bank 2 Sensor 1 and finds high voltage present. The heater is an integral part of sensor function that is used to heat the oxygen sensor to operating temperature until your 2003 Mercury Grand Marquis warms up. Oxygen sensors must be at operating temperature to provide accurate readings to the ECM for air fuel ratio control. This code may be seen with P0051.

What causes the P0052 code?

• Bank 2 Sensor 1 failure
• Open or shorted wiring
• Damaged or poor connections
• ECM has failed
• Oxygen sensor heater failure

What are the symptoms of the P0052 code?

The ECM checks for proper signals from all of your 2003 Mercury Grand Marquis 's sensors multiple times a second. When high voltage is found in the heater control circuit, the ECM triggers a Check Engine Light on the dashboard. In some circumstances, your 2003 Mercury Grand Marquis may exhibit lower than normal fuel economy and run poorly.

How does a mechanic diagnose the P0052 code?

• Hooks up a scan tool to your 2003 Mercury Grand Marquis 's OBD2 port to read live sensor data and check for any codes present

• Uses the freeze frame data associated with every code to determine what conditions your 2003 Mercury Grand Marquis was under when the code was set

• Clears the code and performs a test drive with the scan tool hooked up to monitor sensor data and observe if the code returns

• If the code returns, performs a visual inspection of all wiring and connectors in the circuit, to rule them out

• Observes the oxygen sensor data stream to inspect sensor operation

• If everything checks out this far, performs a manufacturer-specific test of the ECM (varies by make and model; no steps should be skipped.)

Common mistakes when diagnosing the P0052 code

P0052 can be a simple code to diagnose when all diagnostic steps are followed in the proper order and all tests are performed. A professional level scan tool that shows live sensor data will be required to properly diagnose any faults present.

How serious is the P0052 code?

The most common symptom is only the Check Engine Light being observed by the driver. In the chance that poor fuel economy or rough engine running is noticed, care should be taken when driving to ensure safety until the code can be diagnosed and repaired.

What repairs can fix the P0052 code?

• Bank 2 Sensor 1 replacement
• Repair wiring or connection issues
• Fuse replacement if short is found
• ECM replacement

Additional comments for consideration regarding the P0052 code

Any quality mechanic will own a scan tool capable of reading live sensor data.

When the heater circuit is found to have failed for the oxygen sensor, the sensor must be replaced. The heater is internal to the sensor and is replaced as a single unit.

Need help with a P0052 code?

Check Engine Light

P0052

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