Hello I, new to this forum I'm Mayra from NY.
The problem is I have a 2003 Ford Explorer that the timing chain broke. I ended up replacing the engine I was told it be the best thing to do. Soon after the repair was done the check engine light came on; I took the car back to the shop to check the light and they said there wasn't a problem that it was only showing low octane to use higher octane fuel. I switched to premium I have already filled the tank 3 times since with premium. The light went off a while then came back on then again shut off and it's been on a couple days straight. I'm going to take it to diagnose again before the warranty on the engine repair is over (got 90 Day 3000 mile warranty)

Is it normal for the light to go on because of octane? I'm afraid there be a problem with the replacement engine I couldn't afford a new one so we got a used one with 40,000 miles on it. The mechanic SEEMS nice but I am now not sure if he just does not want to have to replace anything again since it still has the warranty. He said it may just be a freak light that just comes on, but it never did before.

 

Have the installing shop/mechanic read the code, post it here, or take it to Autozone or one of the other parts vendors and have the them read the code... Most have code readers and should be free.. It'd be easier to help if there was clarification as to DTC set... Are there any performance/driveabilty problems? Stumble/misfire,unstable idle, pinging ect.?