Help! Service Engine Soon Light!

[C4_Lover]

Hello all, the service engine soon light on my 94 vert only comes on when I'm on the highway at constant speed. ;help Around town the light will not come on. I just had a service done on the car which included: fuel filter, wires and plugs etc...
If anyone has any info please let me know. Thank you.

 

[redvett]

You will need the codes read for any help.

Hello all, the service engine soon light on my 94 vert only comes on when I'm on the highway at constant speed. ;help Around town the light will not come on. I just had a service done on the car which included: fuel filter, wires and plugs etc...
If anyone has any info please let me know. Thank you.

 

[Schrade]

Get your super-duper scanner out of your desk, and plug in:

Post back up with the H history DTC.

 

[C4_Lover]

Took the Vette to my friends shop this morning. He scanned it and it showed the left O2 sensor. I decided to have both sensors changed. Replaced with Genuine GM Parts lol.
What a bear of a job. Sensors were frozen, rusted in place, you name it. Had to be re-threaded after they were removed. Both were clogged with carbon and the left one looked like it might have been damaged by coolant when service was done.
Anyhow, parts and labor $300.00
I will say there is a noticible difference in the way the car runs. Even throttle response seems better, and
I should get better gas mileage!

 

[Rex S]

O2 sensors degrade over time and a new set does wonders for the engine, kinda like changing shocks, you don't realize how bad they are 'till the new ones are in.

 

[C4_Lover]

O2 sensors degrade over time and a new set does wonders for the engine, kinda like changing shocks, you don't realize how bad they are 'till the new ones are in.

I agree 100%. The new O2 sensors make the car run great, but I just got back from a 100 mile trip and there seems to be alot of carbon buildup on the tips of my Magnaflow exhaust. Is this normal?