Check engine light
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Check engine light
Started up the EX after work today and the check engine light popped on. Checked the code and got a P0720. Put in reverse and then drive. Ex started to sputter like it wanted to die then I gave it some gas and it took off. About a mile down the road the light went out. Been reading up on it and seeing what other people are saying and it is all over the map. Some say it's the OSS, some say it's the battery, some say its coil packs and plugs... wondering if anyone else ran into this?
Tuned
Joined: Sep 2019
Posts: 418
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From: Tacoma, WA
Started up the EX after work today and the check engine light popped on. Checked the code and got a P0720. Put in reverse and then drive. Ex started to sputter like it wanted to die then I gave it some gas and it took off. About a mile down the road the light went out. Been reading up on it and seeing what other people are saying and it is all over the map. Some say it's the OSS, some say it's the battery, some say its coil packs and plugs... wondering if anyone else ran into this?
From AllData:
Output Shaft Speed (OSS) Sensor
The output shaft speed (OSS) sensor is a magnetic pickup that provides transmission output shaft rotation speed information to the powertrain control module (PCM).
The output shaft speed (OSS) sensor is mounted externally on the top of the transmission extension housing. The PCM uses the OSS sensor signal to help determined electronic pressure control (EPC) pressure, shift scheduling and torque converter clutch (TCC) operation.
Laughing Gas
Joined: Jan 2020
Posts: 831
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From: Greenville, TX
Here's a live recording from my Blue Driver scan tool. Elapsed time, from left to right. Coolant temp is the steady blue line that runs through the middle of the photo. Engine Speed (RPM) is the other blue line that's lower and more jagged (showing the shifts as I'm accelerating).
The Teal line shows my computer's vehicle speed reading. In my case, the glitch only happens when I stop. Notice how around 1:27, as I'm approaching a stoplight, the reading goes from 0 mph to 75.
OSS malfunctioning around 1:27
The computer would then upshift. To get moving again, I manually drop my shifter to 1, then pop it back to D once I'm doing 8-10 mph. Around 2:08, you can see it going back to normal as I move.
I haven't had the front left wheel speed codes show up in ages. I replaced the sensor and still got the error for a little bit, then it just stopped throwing those.
I still get my OSS codes, but very, very rarely. How did I fix it? My 5Star performance tune keeps it from upshifting
For me, that's enough for now.P.S. - my speedo was never erratic. From what I understand, that reading comes from your rear differential ABS sensor.
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I also did notice the overdrive light on my shifter flashing as well. One thing I will say is my truck was running great up until this point. My ******* left my light bar on over night, must have accidentally hit the button when I was wiping down the interior. So it drained my battery and needed to be jump started. After i got it started i ran it for about 20 minutes, shut it off and tested the battery, which tested good. Not sure if this is what caused it by wiping out the memory, I doubt it but thought I would add this in here to see if anyone has actually ran into this issue. I am replacing the battery today also with a factory motor craft battery. Then I will do the ohms test. We will see what happens. I bought the EX with 136k miles and now it's at 177k and I haven't changed the plugs or the coil packs and dont know if they have been replaced before I got it, so maybe I'll have those replaced sometime soon too just for preventative maintenance...
Laughing Gas
Joined: Jan 2020
Posts: 831
Likes: 171
From: Greenville, TX
I also did notice the overdrive light on my shifter flashing as well. One thing I will say is my truck was running great up until this point. My ******* left my light bar on over night, must have accidentally hit the button when I was wiping down the interior. So it drained my battery and needed to be jump started. After i got it started i ran it for about 20 minutes, shut it off and tested the battery, which tested good. Not sure if this is what caused it by wiping out the memory, I doubt it but thought I would add this in here to see if anyone has actually ran into this issue. I am replacing the battery today also with a factory motor craft battery. Then I will do the ohms test. We will see what happens. I bought the EX with 136k miles and now it's at 177k and I haven't changed the plugs or the coil packs and dont know if they have been replaced before I got it, so maybe I'll have those replaced sometime soon too just for preventative maintenance...
Plugs for sure, the coils only as needed. It wouldn't hurt to order a spare Denso or two.
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kennybrown
1987 - 1996 F150 & Larger F-Series Trucks
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Nov 7, 2012 06:40 PM
