Oxygen sensors measure the oxygen content in the exhaust so the engine computer can keep the fuel mixture correct. When one goes lazy or fails, fuel economy drops, emissions rise and the check engine light comes on. AutoTech Clinic tests and replaces oxygen sensors at 24100 Michigan Ave in Dearborn, usually the same day.
We look at the live sensor waveform rather than just the code. A sensor that switches too slowly still reports a plausible value, and only the live data shows that it has gone lazy.
- How Long
- About 1 to 2 hours for most sensor replacements.
- Same Day
- Usually finished the same day.
- Vehicles
- Foreign and domestic, cars through trucks.
Signs You Need Oxygen Sensors and Emissions
- A check engine light with an oxygen sensor or fuel trim code
- Fuel economy that dropped noticeably
- A rough idle or a hesitation under acceleration
- A failed emissions test
- A sulfur smell from the exhaust
- Readiness monitors that will not complete before a test
What We Do
- 01
Read Live Sensor Data
We watch the sensor switch between rich and lean and measure how quickly it responds. Speed of response is what separates a healthy sensor from a lazy one.
- 02
Check Fuel Trims
Long and short term fuel trims tell us whether the engine is genuinely running rich or lean, or whether the sensor is simply reporting incorrectly.
- 03
Look for Causes
Exhaust leaks, vacuum leaks, a dirty mass air flow sensor and low fuel pressure all produce sensor codes without a bad sensor.
- 04
Replace With the Correct Sensor
Upstream and downstream sensors are different parts, and wideband sensors are different again. We fit the correct one and use anti-seize on the threads.
- 05
Drive Cycle and Verify
We run the vehicle through a drive cycle so the readiness monitors set, which matters if you need to pass an emissions test.
Lazy Sensors Do Not Always Set a Code
An oxygen sensor degrades gradually. Long before it fails completely it starts switching more slowly, and the engine computer responds a fraction of a second late every time. The mixture is never badly wrong, so no code sets, but you lose a noticeable amount of fuel economy.
The only way to see this is to look at the live waveform and count switches per second. If your fuel economy has dropped and nothing obvious is wrong, this is worth checking.
Why Monitors Matter for Emissions Testing
Vehicle computers run self tests called readiness monitors on each emissions system. If the battery has been disconnected or codes were recently cleared, those monitors reset to not ready, and most testing programs will reject the vehicle even with no fault present.
Setting the monitors requires driving the car through a specific pattern of conditions. We can run that drive cycle for you so the car is actually ready when you take it for testing.
What Affects the Cost
We quote your vehicle specifically after inspecting it, because these are the things that move the number up or down:
- How many sensors your vehicle has, which can be two, four or more
- Upstream wideband sensors, which cost more than downstream sensors
- Sensors seized into the exhaust, which can require heat or extraction
- Whether an exhaust leak has to be repaired first
- Diagnostic time where the fault is not the sensor itself
Call (313) 277-7200 with your year, make and model and we will tell you what to expect before you come in.
Why AutoTech Clinic
AAA Approved
An inspected facility that has to meet AAA standards for equipment and training.
Photos First
You see what we found and approve the price before anything is taken apart.
Same-Day Service
Parts on hand for the vehicles we see most, so you are not waiting on a delivery.