What Does P0548 Mean?
The ECM has detected that the exhaust gas temperature sensor circuit on Bank 2, Sensor 1 is producing a signal below the minimum expected threshold. This low-input condition on the Bank 2 pre-catalyst EGT sensor typically indicates a short to ground in the signal circuit or a failed sensor with abnormally low resistance. The ECM will use a default EGT value which may not provide adequate thermal protection.
Common Causes
35%
EGT sensor signal wire shorted to ground from harness contact with exhaust or chassis components on Bank 2 side
30%
Failed Bank 2 EGT sensor with internal short circuit producing abnormally low resistance
25%
Water intrusion into the Bank 2 EGT sensor connector causing a low-resistance path between signal and ground pins
10%
ECM ground-side driver circuit fault pulling the Bank 2 EGT input low
Diagnostic Steps
1
Step 1: Disconnect the Bank 2 Sensor 1 EGT sensor and check if the ECM voltage reading goes to the expected open-circuit level (near reference voltage, typically 4.5-5V). If it does, the sensor is shorted internally.
2
Step 2: Measure resistance of the EGT sensor element at the sensor connector pins. Near 0 ohms indicates an internal short. Normal reading at room temperature is typically 100-200 ohms.
3
Step 3: With the sensor disconnected, measure resistance from each signal wire to ground at the ECM connector side. Any reading below 10k ohms indicates a wiring short to ground.
4
Step 4: Physically trace the Bank 2 EGT harness, inspecting for melted insulation, chafed wires against brackets, or crushed conduit near exhaust manifold heat sources.
5
Step 5: Repair damaged wiring using high-temperature rated materials. Replace the sensor if out of specification. Verify repair by monitoring live data EGT readings through a full warm-up cycle, comparing Bank 2 to Bank 1.
Estimated Repair Cost
$70 - $300
Parts + labor, varies by vehicle and location
The ECM has detected that the exhaust gas temperature sensor circuit on Bank 2, Sensor 1 is producing a signal below the minimum expected threshold. This low-input condition on the Bank 2 pre-catalyst EGT sensor typically indicates a short to ground in the signal circuit or a failed sensor with abno...
The most common cause of P0548 (Exhaust Gas Temperature Sensor Circuit Low (Bank 2 Sensor 1)) is: EGT sensor signal wire shorted to ground from harness contact with exhaust or chassis components on Bank 2 side
Typical repair costs for P0548 range from $70 to $300, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A falsely low Bank 2 EGT reading prevents proper thermal management of the exhaust system. The ECM may not activate protective enrichment strategies, risking damage to the Bank 2 catalytic converter or turbocharger.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0548 to identify the root cause.
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Quick Info
Category
Powertrain
System
Exhaust / Emission Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
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