P0545 Exhaust Gas Temperature Sensor Circuit Low Bank 1 Sensor 1

P0545 code definition

The P0545 code means that the powertrain control module or PCM has triggered the code because it detects a fault in the exhaust system gas temperature sensor circuit.

What the P0545 code means

A P0545 code is an OBD-II generic code that indicates an issue with the exhaust system gas temperature sensor. The PCM detects voltage variations in the sensor, which it reads as exhaust gas temperature. It then adjusts the air to fuel ratios or the ignition timing to cause the exhaust gas temperature to lower in order to protect the catalytic converter. If it determines that there are variations in the voltage outside of the vehicle manufacturer’s programmed levels, it sends the code.

What causes the P0545 code?

A P0545 may be due to:

• Terminals and connectors that are broken, burnt, corroded or loose is the most common cause
• Internal short in the exhaust gas temperature sensor
• Defective sensor
• Use of aftermarket and off road exhaust systems creating back pressure
• Extreme exhaust leak upstream of the sensor

What are the symptoms of the P0545 code?

Typically, the symptoms of the P0545 code are minimal, and tend to be limited to nothing more than the service engine warning lighting on the dashboard and the code being stored.

How does a mechanic diagnose the P0545 code?

To diagnose the P0545 requires an OBD-II scanner, and mechanic or technician will first clear the codes and retest. They will also do a visual scan of the connections and wiring, first replacing or repairing anything that is shorted, corroded, loose or damaged.

They retest and if the code remains they will then do an inspection on the sensor and all of its circuitry, especially any components near the heated areas of the exhaust system. They may repair or replace damaged components and then use their ohm meter to check the sensors voltage. They may use a heat gun to check the sensor and replace it if needed. They may also test the PCM for system continuity and resistance, replacing and reprogramming if needed.

Common mistakes when diagnosing the P0545 code

A typical mistake made when diagnosing the P0545 code is to assess the oxygen sensors and not the exhaust gas temperature sensor. Some technicians also make the mistake of believing that the exhaust gas temperature sensor and the heated oxygen sensors are a single unit, and often leads to a replacement of the oxygen sensor without fixing the issue that caused the code.

How serious is the P0545 code?

The P0545 code will not prevent the car from operating, but it can be due to extremes of heat in the exhaust system, meaning that if ignored it can eventually lead to harm or loss of the catalytic converter.

What repairs can fix the P0545 code?

To fix the P0545 code, a mechanic will:

• Use the scanner to verify the code, clearing it and retesting to be sure it is authentic. They will use the data and freeze frame information and perform a visual inspection of all wiring.
• If replacing and repairing and electrical components fails to clear the code, they examine the exhaust gas temperature sensor and all of its circuitry, looking at areas where heat is the most intense.
• If fixing and repairing any electrical components does not clear the code, they will then use their ohm meter to check the sensor resistance, and if it is within manufacturer’s levels they then test it with a heat gun gauging if it does not cause the resistance to decrease when heated, it will be replaced.
• If these yield no results, they will move on to the PCM, testing the continuity and replace it if needed.

Additional comments for consideration regarding the P0545 code

It is rare that this code leads to the need to replace the PCM. Instead, check the wiring and don’t ignore any oxygen sensor codes that appear in the freeze frame data. Rule these out before replacing the sensor or the PCM.

Need help with a P0545 code?

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