P0548 — Exhaust Gas Temperature Sensor Circuit Low (Bank 2 Sensor 1)

What exactly does P0548 mean?

P0548 means the control module detected a low signal from the exhaust gas temperature sensor identified as Bank 2, Sensor 1, or a related short-to-ground condition in that circuit.

Is P0548 the same as an oxygen sensor fault?

No. P0548 concerns the exhaust gas temperature sensor, which measures exhaust temperature and can provide feedback to the powertrain control module; it is not a conventional upstream or downstream oxygen sensor.

Can the vehicle be driven with P0548 stored?

Usually yes for limited driving, because P0548 alone may not create an immediate safety hazard. However, incorrect sensor feedback can affect engine operation, so diagnosis and repair are recommended before long or high-load trips.

How can I determine whether the sensor or wiring causes P0548?

Use the service wiring diagram to test the circuit, then disconnect the sensor on a pull-up-style circuit. A voltage rise usually identifies the sensor, while voltage that remains low points to a wiring short, connector problem, or ground fault.

P0548 is an exhaust gas temperature sensor circuit low condition detected on Bank 2 Sensor 1. When the engine control unit monitors this circuit and the voltage signal drops below the expected minimum threshold for a sustained period, it flags this code. The exhaust gas temperature sensor monitors how hot the exhaust stream becomes as it leaves the engine. The ECU uses this data to manage combustion timing and protect emissions components from overheating.

Bank 2 refers to the engine bank that does not contain cylinder number 1, and Sensor 1 denotes the upstream position — in this case, mounted before the catalytic converter. When the signal from this particular sensor reads implausibly low or shorts to ground, the ECU interprets it as a circuit malfunction. Multiple failed drive cycles are typically required before the control module illuminates the check engine light and stores P0548. In most vehicles this fault will not prevent the engine from running, but it can affect emissions compliance, fuel economy, and in some cases trigger a limp-home mode to protect downstream components.

Common Symptoms of P0548

The check engine light is the most obvious indicator that P0548 has been stored. Beyond the warning lamp, drivers often notice increased fuel consumption as the engine management system compensates for unreliable temperature data. Depending on how the manufacturer programmed the affected circuit, the vehicle may enter a reduced-power mode to prevent damage to emissions equipment. The sensor or the system it feeds may operate inconsistently or cease providing data altogether. Other potential indicators include exhaust odor changes and visible smoke, though these are less frequent with this particular code.

What Causes P0548

Wiring and connector problems account for the majority of P0548 failures. The exhaust gas temperature sensor lives in one of the harshest environments in the vehicle, exposed to extreme heat and corrosive exhaust gases. Over time, the pigtail and connectors degrade, leading to poor conductivity. Control module driver faults are less common but possible, especially in vehicles with many miles on the odometer. Sensor or actuator failures occur, as do open or short circuits in the harness from heat damage or physical stress.

• Corroded, loose, or damaged connector
• Control module driver fault
• Faulty sensor or actuator of the affected circuit
• Open or shunted wiring in the circuit

How to Diagnose P0548

A systematic approach keeps you from replacing good parts. First, connect an OBD2 scanner and confirm that P0548 is present. Save the freeze frame data — these snapshots of engine operation at the moment of failure are invaluable for understanding what triggered the issue. Second, check for related diagnostic trouble codes. Codes that appear alongside P0548 often point to the underlying problem and can save hours of guessing. Also look up manufacturer technical service bulletins for your specific make and model — many powertrain codes have documented factory fixes or software updates. Third, perform a close visual inspection of the wiring harness and connectors routed near the exhaust. Look for cracked insulation, corrosion buildup, rubbed-through wires, and connectors that are not fully seated. Fourth, measure reference voltage and ground at the sensor connector with a multimeter. Compare your findings against the specifications in the service manual. Fifth, perform a wiggle test on the harness while watching the live data stream — any signal dropouts or wild fluctuations indicate broken conductors hidden under the insulation. Sixth, clear the code, complete a full drive cycle that recreates the conditions stored in the freeze frame, and verify that P0548 does not return.

Repair Options and Costs

Address the most accessible and inexpensive possibilities before committing to major work. Connector replacement or repair — cleaning corroded terminals, replacing a damaged pigtail, or reseating a loose plug — typically runs $80 to $250 for parts and labor. Control module diagnosis is more involved; if the driver circuit inside the ECM or PCM has failed, expect to pay $300 to $1,000 depending on whether the module can be reprogrammed or must be replaced outright. If testing confirms the exhaust gas temperature sensor itself is faulty, a new unit with installation generally costs $150 to $500.

Overall, fixing P0548 usually costs between $80 and $1,000 depending on which component is at fault. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Can You Drive with P0548?

In most cases the car remains drivable, though you