SES Light On Highway Only
Thread Starter
Intermediate
Joined: Aug 2018
Posts: 44
Likes: 2
From: Apple Country WNY
SES Light On Highway Only
I picked up my 1992 Corvette yesterday (48k miles), and drove it 600 mostly highway miles home. Maybe 30 minutes after hitting the highway, the SES light comes on. It would cycle off and on the rest of the trip. The car ran pretty well at 80MPH on the highway for 7 hours, and thru several construction zones. The performance didn't wow me, but this is my first Corvette so I don't know what I should expect. Mileage was around 17mpg, which didn't thrill me either. Today I drove 40 miles on country roads below 65mph and no light at all. Mileage was exactly the same, 17 mpg. What code reader is compatible with this car? It will be my first investment. Other than that and an intermittent brake warning light during the trip, I was happy with the overall performance. It is a beast on the road! I would love to hear from anyone who has experienced this problem!
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,218
Likes: 1,174
From: Southlake, TX
O2 sensor. That is where I'd start. However, you had no codes. Did the car sit for a long time before you drove it home? If so, you were probably just working through bad gas (which makes the 02 sensor freak out) and letting it stretch.
17 MPG is a little light but I be your car needs a tune up.
17 MPG is a little light but I be your car needs a tune up.
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
Code Reader
See picture above. Cheap and pretty limited information. Now you can get yourself a scanner and actually get meaningful data someone can help you diagnose stuff with. Not as cheap but you get what you paid for. ALDLScan with the Bluetooth unit from 1320 Electronics should work.
The red one or the line on the DIC? I wonder if the brake fluid is low or the sensor is thinking that the brake fluid is low because it is bad.
Thread Starter
Intermediate
Joined: Aug 2018
Posts: 44
Likes: 2
From: Apple Country WNY
O2 sensor. That is where I'd start. However, you had no codes. Did the car sit for a long time before you drove it home? If so, you were probably just working through bad gas (which makes the 02 sensor freak out) and letting it stretch.
17 MPG is a little light but I be your car needs a tune up.
17 MPG is a little light but I be your car needs a tune up.
Last edited by IowaClass65; Aug 23, 2018 at 10:41 PM.
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Very likely an EGR code, you need a scanner or the paperclip trick to pull the codes, that should point you to the problem. That would be unrelated to the fuel mileage, which indicates a possible O2 sensor failure. Your highway mileage should be at least in the 23-25 range. When O2s die, they die slow and rarely give off a code until its really bad.
Last edited by vader86; Aug 24, 2018 at 08:55 AM.
