P0145: The oxygen sensor farthest downstream on bank 1 (sensor 3) is responding too slowly
O2 sensor slow response, bank 1 sensor 3
Severity: Monitor
An oxygen sensor circuit fault mostly affects emissions and fuel economy, and TroubleCodes.net reports little or no drivability change, so book a repair rather than stopping.
P0145 in short
P0145 means the third oxygen sensor on bank 1, the side with cylinder 1, is responding too slowly to changes in the exhaust. Common causes are a worn or contaminated sensor or damaged wiring. The car usually drives normally, so book a check; fix any misfire or fuel trim codes first.
Oxygen sensors report how much oxygen is left in the exhaust, and the computer expects their signal to change promptly. P0145 sets when the signal from bank 1 sensor 3 changes more slowly than it should.
Sensor 3 is a third sensor on the exhaust of bank 1, which is the side of the engine with cylinder 1. Which physical sensor that is depends on the engine, so check a diagram for yours.
TroubleCodes.net says the engine should run properly before this code is diagnosed, because misfires and fuel trim problems can disturb the sensor signal.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Worn, fouled or contaminated oxygen sensor
Common general cause- Why it ranks here
- TroubleCodes.net lists defective and fouled sensors among the causes, and an aged sensor reacts slowly.
- What would change this
- Deposits or discolouration on a removed sensor, or sluggish live data, raises it.
Cause 2: Damaged, corroded or disconnected sensor wiring or connector
Common general cause- Why it ranks here
- TroubleCodes.net lists damaged or corroded wiring and connectors first among the causes.
- What would change this
- Visible damage or a signal that drops out when the harness is wiggled raises it.
Cause 3: Fuel or misfire problem upsetting the exhaust
Possible — needs testing- Why it ranks here
- TroubleCodes.net says fuel trim and misfire codes must be fixed before diagnosing this code.
- What would change this
- Other fuel trim or misfire codes stored with it raise this.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Read all codes and freeze-frame data and note any fuel trim, misfire, exhaust or other oxygen sensor codes stored with P0145
IfFuel trim, misfire or other sensor codes are also stored
It meansRepair those first; they can disturb this sensor.
IfP0145 is the only code
It meansInspect the sensor wiring next.
Step 2: With the exhaust cold, inspect the sensor wiring, connector and related fuses for damage, corrosion and routing near hot parts
Warning:Let the exhaust cool fully before touching the sensor or its wiring. Back-probe connectors gently, never pierce insulation, and follow the wiring diagram for your engine.
IfDamaged wiring, a corroded connector or a blown fuse is found
It meansRepair it.
Points to: Damaged, corroded or disconnected sensor wiring or connector
IfWiring looks good
It meansTest the sensor electrically.
Step 3: Unplug the sensor and test its resistance and the circuit continuity, voltage and ground against the specification for your engine
Warning:Let the exhaust cool fully before touching the sensor or its wiring. Back-probe connectors gently, never pierce insulation, and follow the wiring diagram for your engine.
IfResistance or readings are out of specification, or the removed sensor is contaminated
It meansThe sensor has failed; replace it.
IfSensor and circuit test good
It meansLook at the remaining causes.
Symptoms
- Check engine light
- Reduced fuel economy
- Hesitation or rough idle in some cases
How to fix
Step 1: With the exhaust cold, inspect the sensor wiring and connector for damage, then clear the code and drive through several cycles to see if it returns.
Parts and cost context
- Oxygen (O2) sensor:Use the correct sensor for that bank and position on your engine; sensors in different positions are often different parts.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
FordYour car
2023–2024 · F-250 Super Duty
Supported by vehicle dataFord TSB 24-2066 says some 2023-2024 Super Duty vehicles with the 6.7L engine built on or before 02-Jan-2024 may show a check engine light with P0133, P0139 and/or P0145 stored in the PCM. Whether it is still current is not verified.
2023–2024 · F-350 Super Duty
Supported by vehicle dataFord TSB 24-2066 says some 2023-2024 Super Duty vehicles with the 6.7L engine built on or before 02-Jan-2024 may show a check engine light with P0133, P0139 and/or P0145 stored in the PCM. Whether it is still current is not verified.
2023–2024 · F-450 Super Duty
Supported by vehicle dataFord TSB 24-2066 says some 2023-2024 Super Duty vehicles with the 6.7L engine built on or before 02-Jan-2024 may show a check engine light with P0133, P0139 and/or P0145 stored in the PCM. Whether it is still current is not verified.
TSB 24-2066Status unverified
Super Duty 6.7L: MIL with P0133, P0139 and/or P0145 (supersedes 24-2036)
2023–2024f-250-super-duty, f-350-super-duty, f-450-super-duty · issued · NHTSA 10252546
Ford bulletin saying some 2023-2024 F-Super Duty pickups with the 6.7L engine, built on or before 02-Jan-2024, may show a check engine light with P0133, P0139 and/or P0145 stored in the PCM. It supersedes article 24-2036 to update the vehicles affected. Only the NHTSA summary was read.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
Related codes
No curated relationships for P0145 yet.
Sources and review
- P0145 trouble code page
- On-Board Diagnostic Trouble Codes (generic code title list)
- TSB 24-2066: Super Duty 6.7L: MIL with P0133, P0139 and/or P0145 (supersedes 24-2036)
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error