P0053 OBD-II Trouble Code: HO2S Heater Resistance (Bank 1 Sensor 1)

P0053 code definition

HO2S Heater Resistance (Bank 1 Sensor 1)

What the P0053 code means

This code means the Heated Oxygen Sensor (HO2S) Resistance is out of range on engine bank 1 (side of engine with cylinder #1) and the sensor upstream or in front of the catalytic converter.

What causes the P0053 code?

• Faulty HO2 sensor
• Damaged or disconnected electrical connector at the oxygen sensor
• Faulty or shorted wiring in the oxygen sensor circuit
• Blown fuse for the HO2S sensor
• Low or excessive fuel pressure
• Vacuum leak on the engine
• Excessive exhaust leaks
• Faulty ECU (Engine Control Unit), in rare cases

What are some of the symptoms of P0053 code?

Possible symptoms from the O2 sensor heater failure include the O2 sensor not giving the proper reading as fast as it should, in which case the ECU would go into failsafe mode until the system is repaired. The Check Engine Light would then come on once the ECU detects the O2 sensor problem. The failsafe mode will cause different drive complaints, depending on the manufacturer programming.

How does a mechanic diagnose the P0053 code?

Normally the Engine Warning Light comes on the dash to indicate a problem. The mechanic diagnoses the problem using an OBD-II scanner to determine the trouble code. The mechanic can then start by checking the resistance across the wires of the HO2S, which should be about 8 ohms with a range of 7-9 ohms. If the resistance is outside of the acceptable range, then the sensor is bad and must be replaced. If the resistance is within the acceptable range, then the problem may be in the wiring, which must be carefully checked for the sensor being disconnected, a bad connector, or bad wiring caused by the proximity of the exhaust system.

Common mistakes when diagnosing the P0053 code

Do not immediately assume the HO2S is bad and replace it. You must follow the test procedure to ensure that the wiring and other components are in good condition. Most of these problems are related to wiring touching the exhaust system.

How serious is the P0053 code?

This code has several causes, but the vehicle may operate normally. This code tends to confuse the ECU, which can default to operating okay, but it may cause excessive fuel consumption and poor performance. It is important that the vehicle is properly diagnosed at the first opportunity.

Often times, if the Engine Warning Light comes on immediately at start up, the OBD- II system can be reset and the vehicle will operate normally.

What repairs can fix the P0053 code?

Have a certified technician verify the code with a scanner, reset the fault codes, and perform a road test. If the P0053 code returns, then follow the test procedure.

Using the OBD-II scanner, reset the code and test the vehicle again to see if the Engine Warning Light comes back on, and the code returns after the engine is at operating temperature. If it comes back, then check the resistance on the wiring of HO2S to ensure that it is about 8 ohms, plus or minus 10%. If it is normal, then check the wiring, including the connector to the sensor, and on up to the main wiring loom to ensure that the wires are not broken, frayed, damaged or melted to the exhaust system. Repair wiring and connectors with correct parts and wiring type to ensure original operation.

This sensor and wiring are especially susceptible to damage as they are close to the body; it is imperative that the wiring be secured away from the exhaust as much as possible. Removing these sensors is usually difficult as they are very tight, and often the threads are damaged when removed, which requires that the bung on the exhaust be re-tapped or replaced. If the sensor threads are damaged, it is best to replace the sensor.

These sensors are very important to the operation of the vehicle to ensure smooth and economical function. It becomes all too easy to make a repair in haste, only to find you now have more problems; expensive problems.

Additional comments for consideration regarding the P0053 code

Many vehicles with mileage over 100,000 have momentary sensor problems that usually occur during start up, or prolonged stress situations on the drive train. If the Engine Warning Light comes on and the vehicle seems to be operating normally, the OBD-II system can be reset by using the scanner, and the problem may not reoccur. This is why it is important to verify the fault firstly, and reset it before doing any repairs.

Need help with a P0053 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.