Check Engine Light

My check engine light came on after I had driven the car only 23 miles. I checked the gas cap and waited. The light went out after a bit but came back on after a few more miles. After a bit more, it went out and has stayed out. Posts on the Yahoo Prius page have seemed to indicate the same situation for other owners. After just under three months and about 2200 miles of driving the check engine light has not come on again.

Bruce Webster

 

Yeah, had it come on at around 30-50 miles, stayed on for a few days - close to 3 days, then it went out the day they were supposed to check it (of course!). Apparently it has to do with residual carbon being cleaned out of the system, so it's no worry, as long as the light doesn't come back on.

-m.

 

My dealer told me it was the coating on the emissions system triggering the oxygen sensor. He suggested I bring it in, and they confirmed it was the O2 sensor, and they shut off the warning light. He then suggested I drive it hard for a while on the freeway, to burn off the rest of the coating. He said it was caused by driving the car TOO gently. I asked What about the break-in period. He said Don't worry about that. So I drove it medium-hard for a while. I never floored it, but I brought it gradually up to freeway speed, and then slowed down, repeatedly, as per his instructions, to get the emissions system good and hot. I've had no problem since.

(There's no traffic on I-29 north of Fargo, so there's no safety issue about the fast/slow driving. I kept my speed steady while being passed, once every 5 minutes or so.)

 

I had the same problem. It stayed on for three days. Then went off just before I took it to the dealer. They checked it and said they couldn't find any error codes.

 

I had the same problem. The check engine light came on during my first drive home from the dealership. Obviously disgruntled they took my car into service the next day and stated exactly (oddly almost word for word) what Daniel wrote above. I drove it on the highway but probably too "lightly" and not for long enough since the light came back on during my trip home from the dealership again. This wonderful website had a past post regarding this issue and people commented that their light went off on its own after 52 miles. Sure enough mine went off after 56. Hopefully this is your issue as well.

 

Ya, this has been hashed-out a lot on the yahoo group.

The Prius has some sealant in the exhaust system which will burn off during the first 100 miles or so of use.

It's not a problem, but as with any check-engine light, best to get it looked at (it's free, after all!).

Dave.

 

My check engine light went on at 250 miles. After three days the dealer reset and said I probably filled the tank with the engine on.

The light came on a week later and stayed on for 6 days until I could get to the dealer. After waiting two hours at the dealer they said that I needed a new gas tank and dashboard heat/cooling sensor. They gave me a loaner car for the 3 weeks it took to get the gas tank in.

No problems with the check engine light with the new gas tank and sensor. The bigger benefit was I ran the tank down and with no trouble put 10.6 gallons of fuel in it. The gauge reads more consistently and its easier to fill.

They also cautioned that generally it is OK to drive the car with the check engine light on but if it flashes pull over immediately.