2002 Prius Master Warning

I have a 2002 Prius that developed an interesting habit last winter. Whenever the overnight temperature gets down around freezing upon starting the car the next morning I get a Master Warning and the car turns itself off. Of course the manual says to immediately contact Toyota Service but instead I just restart the car and it runs and drives fine but the Master Warning will not turn off until the ambient temperature goes up above freezing. The colder it is the more insistent the car is about the Master Warning because if it is very cold I sometimes have to restart two or even three times.

I would call and ask Tom and Ray on the air but they seem like really nice guys and I don’t want to embarrass them.

So, you’ve been getting this “Master Warning” message for nearly a year and you’ve ignored it completely, despite the recommendation in the owner’s manual.

Is that correct?

Do you think they put the “Master Warning” on the car just to annoy you on cold mornings? I seriously doubt it.

I’m not an expert on the Prius, but there MUST be a reason the warning light comes on when the temperature is at or below freezing. What that reason is I have no idea, but perhaps someone at the Toyota dealer might know.

I suggest, considering the enormous complexity of the Prius drive train, that you stop ignoring the importance of the “Master Warning” light.

I’m willing to bet $50 right now that you will completely ignore my suggestion and go through the coming winter cursing the “Master Warning” light every day as you start and restart your Prius.

Until the day it doesn’t start, no matter how many times you try.

Then the “Master Warning” light will get your full attention.

Oh I never curse the master warning light, or anything else on my cars, why would I do that? Cars are interesting mechanical devices, I bought this one because I was curious about the current hybrid technology and wanted the experience of operating one. If it doesn’t start I’ll just drive one of the others.

It was much more interesting to go through various scenarios in the beginning to figure out when the Master Warning came on. There were numerous possibilities like whether or not I had parked on a hill or used the emergency brake (that was a weird Ford electrical problem I had once), or left the battery in a low charge state and only as the fall progressed into winter did the cause become apparent because I live in a fairly warm climate area.

And my local Toyota dealer? Well I took the car there soon after I first purchased it for an oil change and because it is the Gen 1 (USA, Gen 2 Japan) body style the service writer argued with me about whether or not it was a hybrid Toyota until I took him to the back of the car and showed him the car nameplate. Not too comforting but I’m not disparaging the abilities of the mechanics based on the ignorance of a service writer.

I just asked a question and certainly don’t need a lecture on how I care for my cars. It sounds like you are transportationally disadvantaged, I hope you live near a bus stop.

No, there are no bus stops anywhere near my house. I rely on my vehicles to get me where I need to go every day.

Sorry if I seemed condescending. No offense intended. We get lots of posts from Prius owners who have no idea what they’re doing.

Re-read your original post. You didn’t say, “I’ve meticulously maintained this vehicle,” or anything similar. How were we to know you’re not just another Prius owner who has no idea what he or she bought?

You still haven’t explained why you’re ignoring the “Master Wanring” light.

Sorry, I’m educated in a science field, own a company that maintains complex mechanical flying machines and am currently looking for an electric vehicle to purchase. I bought the low mileage, dealer maintained 2002 Prius in 2006 at a really reduced price and I don’t hesitate to have my cars maintained by professionals (it’s professional courtesy, I don’t work on my cars, they don’t work on their planes).

It was an unusual occurrence and the reason I reached down and restarted the car (after consulting the owner’s manual) the first time it happened is because the manual says if you run a Prius out of gas it throws all kinds of warnings that don’t reset until you have started the car several times after putting gas in it.

It was just curiosity and I do admit if it had melted down into a little puddle or burst into flames I would have been embarrassed and very sorry to have destroyed a perfectly fine vehicle.

I promise if it happens again this winter I will immediately take it in and have it put on a diagnostic machine and if not I will tell them of the problem at the next regularly scheduled maintenance interval.