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DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P0549

P0549Exhaust Gas Temperature Sensor Circuit High (Bank 2 Sensor 1)

P0549 means the powertrain control module (PCM) has detected an abnormally high voltage on the exhaust gas temperature (EGT) sensor circuit for bank 2 sensor 1, which is the sensor located before the catalytic converter on the bank of cylinders that does not contain cylinder number one. The PCM interprets this high voltage as an excessively hot exhaust stream or a circuit fault, and it sets the code to protect the engine and emissions system.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Reduced engine power or limp mode if the PCM derates the engine for protection
  • Poor fuel economy or altered shift feel as the PCM adjusts fueling and torque management
  • In rare cases, a rough idle or hesitation if the sensor signal is used for fuel control
  • No visible signs at all until a scan tool reveals the stored code

Common causes, most likely first

  1. A failed EGT sensor that internally shorts to voltage or has drifted out of range
  2. Damaged or chafed sensor wiring shorted to voltage, especially near hot exhaust components
  3. Corroded or loose connector pins at the sensor or PCM harness
  4. An open ground circuit for the sensor, causing the signal voltage to float high
  5. A PCM internal fault biasing the sensor reference voltage
  6. Extremely high actual exhaust temperatures from overfueling or a restricted exhaust, though this is less common

How to diagnose and fix it

  1. Connect a scan tool and record the freeze-frame data and live EGT sensor voltage to confirm the high reading
  2. Visually inspect the sensor, connector, and wiring for damage, corrosion, or contact with hot surfaces
  3. Measure the sensor signal voltage with a multimeter and compare it to the manufacturer's specification
  4. Check the sensor ground circuit for excessive resistance or an open circuit
  5. Perform a voltage drop test on the signal wire to rule out a short to voltage
  6. If the circuit tests good, replace the EGT sensor with a known-good unit and clear the code
  7. After repair, road-test the vehicle and verify the monitor runs without resetting the code

What a high EGT reading really tells you

  • A high voltage on an EGT sensor circuit often means the sensor ground is open, not that the exhaust is genuinely hot, so check grounds before condemning the sensor.
  • Bank 2 sensor 1 is the pre-catalyst sensor on the bank without cylinder one; mixing it up with the post-catalyst sensor leads to replacing the wrong part.
  • Some vehicles use a thermocouple-type EGT sensor whose signal can be skewed by a poor connection at the sensor pigtail, which is easy to overlook.
  • The PCM may set P0549 intermittently if the wiring harness rubs against a heat shield only during certain engine movements, so wiggle-test the harness while watching live data.
  • A failed EGT sensor can cause the PCM to command excessive fuel for protection, which may eventually damage the catalytic converter if the code is ignored.

Can I keep driving with P0549?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy loads, towing, or sustained high-speed driving because the PCM may be adding fuel for protection and could damage the catalytic converter. If the engine enters limp mode or you notice a strong burning smell, stop driving and have it towed.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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