P0055 OBD Error Code: Problem & Solutions

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When this code is set it means that the Engine Control Module (ECM) has detected a problem with the amount of resistance in the heater circuit for the third oxygen sensor on bank one of the engines.

It normally has direct implications on the fuel delivery system causing increase in fuel consumption as well as engine stalling and not starting. The first indication of the fault in always the check engine light and immediate loss of power form the engine, thus implying Code P0055 error.

The most common cause for this code is the heater inside the oxygen sensor burning out. When this happens, it will cause the circuit to either incomplete, or open, or short out. Essentially, the ECM has a pre-set amount of resistance that it wants to see for the sensor to heat up properly.

When the circuit is open, there will be an infinite amount of resistance because current can no longer travel along a complete path. When the sensor shorts out, the resistance is too low and the sensor will not heat up enough for the sensor to operate properly.

What causes this problem with the Heater Circuit Resistance (Bank 1, Sensor 3)?

• The most common reason can be a blown or burnt fuse
• Faulty Engine Control Relay
• Damaged Heated Oxygen Sensor leading to broken circuit
• Open or short of oxygen sensor harness
• Improper data transmission due to faulty circuit connection

1. Heated Oxygen Sensor - A faulty sensor will not be able to measure the correct amount of oxygen in the exhaust and is a major reason behind the OBD Error Code P0055 flashing on the ECM and immediate replacement is required.
2. Heated Oxygen Sensor Harness - Damaged Sensor harness disrupts the sensor circuit. It is advised the replace with the new one. Buy quality auto parts from us.
3. Heated Oxygen Sensor Connector - A faulty connector hampers the fuel economy and the exhaust system. Replace your old connectors now.
4. Engine Control Module - Faulty ECM affects the electrical and subsystems performance directly. Replace the faulty components immediately.
5. Powertrain Control Module - PCM problems are rare but have to addressed with utmost importance. Replace then now!
6. Catalytic Converter - Faulty catalytic converters have to be immediately replaced as it affects the fuel economy and the problems with the exhaust and emissions.
7. Diagnostic Tool - In order to be detect and diagnose the reasons for the OBD error, it’s important to use professional grade diagnostic tools. Buy quality diagnostic tools from us.

No perceptible symptoms are found for an OBD P0055 error. The major symptom is that sensor begins to stop operating correctly as the exhaust stops heating up sufficiently, as opposed to the built-in heater heating it up. This causes increase in emissions coming out of the tailpipe, which results in Check Engine Light is illuminated.

Common Symptoms

• Loss of response from engine and throttle
• Increased fuel consumptions
• Check Engine Light On
• Black smoke coming from the exhaust pipe

Replacing the below mentioned components can be the most common solution to correct the OBD Code P0055 error;

• Replacing of faulty Heated Oxygen Sensor
• Repairing the broken, damaged and burnt circuit wiring of the sensor
• Effectively checking the troubleshooting ECM/PCM and replacing the components if needed

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Following are the steps involved in diagnosis of Error Code P0055.

• First step is the visual inspection of the sensor and its associated wiring and harness to check for any defaults. Damaged wiring or connectors are the main cause of the problem most of the time.
• The next step after the visual inspection is to measure the heater resistance in the oxygen sensor.
• Unplug the connector for the oxygen sensor and use the multimeter to measure the resistance, across the heater terminals.
• If the sensor reading the not as per the desired standards, then the sensor needs to be replaced immediately.
• The next step is to measure the resistance of the wiring from the ECM to the oxygen sensor plug, if the sensor is found good.
• If after all the checks, everything works well, then most probable problem can be with the Engine Control Module itself. The ECM usually activates and grounds the heater circuit. The main problems can be of the circuit; ECM contacts getting burnt which can cause a higher than normal resistance reading. This would definitely cause the P0055 code to set.

Common Mistakes When Diagnosing OBD Code P0055

The first plan of action mostly constitutes of replacement of faulty oxygen sensor. However, it’s important to know that there are many reasons for the fault in the heater circuit. It may be issues with the wiring and other modules as well. There can also be default in the ECM/PCM which require changing. Thus, proper technical assistance is required to come to a right conclusion.