A/F Sensor Code & Live Log help
06-17-2018, 10:20 PM
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A/F Sensor Code & Live Log help
Car pulled the P1278 code (A/F Sensor 1 Bank 1), my live log looks like this
Sensor 1 Voltage .260-.275 Sensor 2 Voltage constant .280
Sensor 1 STFT +3.8-13.0 Sensor 2 STFT constant +99.2
No issues with drivability & idle seems fine. What the **** is going on? 99.2 seems insanely high first off. And sub .3 voltage seems low to me. Also why does the driver side vary while the passenger side is constant? What does it seem like the issue would be? Faulty Bank 1 sensor or both or am I looking at something way more? Exhaust leak is possibility may need new gaskets for Art Pipes. Didn’t have code immediately after install though, been about a month & a half since & I feel like that’d be more of sensor 2. Anyone have some knowledge on what correct range of these values should be either? Thanks. Can pull more diagnostics if needed.
Sensor 1 Voltage .260-.275 Sensor 2 Voltage constant .280
Sensor 1 STFT +3.8-13.0 Sensor 2 STFT constant +99.2
No issues with drivability & idle seems fine. What the **** is going on? 99.2 seems insanely high first off. And sub .3 voltage seems low to me. Also why does the driver side vary while the passenger side is constant? What does it seem like the issue would be? Faulty Bank 1 sensor or both or am I looking at something way more? Exhaust leak is possibility may need new gaskets for Art Pipes. Didn’t have code immediately after install though, been about a month & a half since & I feel like that’d be more of sensor 2. Anyone have some knowledge on what correct range of these values should be either? Thanks. Can pull more diagnostics if needed.
Last edited by Moveovr; 06-17-2018 at 10:23 PM.
06-20-2018, 04:02 AM
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no I actually mean bank 1 sensor 1 & bank 1 sensor 2 so disregard the sensor 2 I realize it’s the pre & post cat sensors. Which would make that the 02. Not sure what I was thinking at the time logging the 02 vs an A/F lol. Definitely SHOULDVE been bank 1&2. Guess my main question is, what should my A/F (sensor 1 bank 1) numbers look like? And I guess is it normal for the 02 to be a 99.2 anyways? I’ll get the sensor 1 bank 2 & post that in a little bit to compare though. Would make much more sense. Good catch
06-22-2018, 01:43 AM
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Your car is like mine. Your reading for sensor 1 bank 1 is just s bit low. It should be around 0.300 Volts. Here's a post that explains the values you should see for banks 1 and 2:
https://my350z.com/forum/engine-and-...l#post10943127
https://my350z.com/forum/engine-and-...l#post10943127
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06-22-2018, 01:48 AM
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Have you noticed any actual issues with the car or should I just clear the code & go on with my day? +13.0 does still sound like something may be off though. It’s getting swapped out at the end of the year anyways.
Last edited by Moveovr; 06-22-2018 at 01:52 AM.
06-22-2018, 03:54 AM
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A P1278 code indicates the A/F sensor response from rich to lean is slow, and the most probable cause would be the sensor itself. Your voltage reading of 0.260-0.275 Volts shows your running a bit rich, confirming the code. The STFT reading is probable the result of the sensor going bad. Changing the sensor is probably your best bet.
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