OBD-II Code
P0145
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$110–$560
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
P0145 means the bank 1, sensor 3 O2 sensor is responding too slowly — the ECM monitors how fast the sensor voltage transitions from low to high (rich-to-lean and lean-to-rich) during the catalyst monitor sweep, and a healthy narrow-band sensor should complete a full lean-rich transition in under 100-300 ms depending on the manufacturer's threshold.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP0145 means the bank 1, sensor 3 O2 sensor is responding too slowly — the ECM monitors how fast the sensor voltage transitions from low to high (rich…
P0145 means the bank 1, sensor 3 O2 sensor is responding too slowly — the ECM monitors how fast the sensor voltage transitions from low to high (rich-to-lean and lean-to-rich) during the catalyst monitor sweep, and a healthy narrow-band sensor should complete a full lean-rich transition in under 100-300 ms depending on the manufacturer's threshold. Sensor 3 sits downstream of the main cat in a triple-sensor exhaust, so its job is to confirm catalyst efficiency, not to run closed-loop fuel control — that means a slow response on B1S3 is almost always physical contamination (silicone from RTV, phosphorus from oil burning, sulfur from fuel) or a sensor at end of life rather than a wiring fault.
Cheapest-first ladder
- Scan live data and watch B1S3 transition time during a snap-throttle test at warm idle — count the milliseconds from the voltage leaving 0.3V to crossing 0.6V; over 400 ms is borderline, over 600 ms is failed.
- Inspect the sensor tip if you can pull it — a white powder coating means silicone contamination (someone used non-O2-safe RTV upstream), a glossy brown coating means oil burning, a yellow-gray ash crust means sulfur from cheap fuel.
- Check fuel trims — if LTFT is over plus or minus 10% on bank 1, the slow response is a symptom of poor combustion, not a dead sensor; fix the trim problem first. The expensive misdiagnosis is replacing the cat ($1,200-$3,000) on a P0145 that was actually a slow sensor caused by an oil-burning engine — the new cat will be ruined inside 10,000 miles.
Vehicle-specific patterns2007-2014 Toyota Tundra/Sequoia 5.7L 3UR-FE commonly throws P0145 from sulfur contamination after extended runs on low-grade fuel — a tankful of prem…
- 2007-2014Toyota Tundra/Sequoia 5.7L 3UR-FE commonly throws P0145 from sulfur contamination after extended runs on low-grade fuel — a tankful of premium plus a 30-minute highway drive often clears it without parts.
- 2008-2014Ford F-150 5.0L Coyote V8 sees P0145 on bank 1 sensor 3 from oil consumption through the PCV system fouling the rear sensor after 100k miles.
- 2010-2015RAM 1500 5.7L Hemi with MDS throws P0145 from cylinder-deactivation residue glazing the bank 1 sensor 3 element.
- 2006-2012Mercedes-Benz ML350/GL450 with the M272/M273 V6/V8 sees P0145 on bank 1 sensor 3 from a degraded sensor element around 90-130k miles — Mercedes pattern that tracks with the balance-shaft service interval.
Estimated repair$110 to $560.
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