Engine always running

Hi everyone,

I have a Prius C with 10,000km / 6,200mi. It recently developed an intermittent issue where the petrol (gas) engine does not shut down at times when the car would normally be in EV mode (downhill coasting, stationary, etc). This does not happen every time, but only on around 50% of trips.

Once the problem occurs, it will continue until the car is completely switched off, regardless of how long the trip is. If I restart the vehicle, the issue will sometimes disappear. I have been in the car driving normally for well over an hour, and the engine has not turned off the whole time. As a result, fuel economy is suffering.

As it's still under warranty, I will be taking it to the Toyota dealer. However I thought I'd see if anyone else had seen this issue, or if anyone knows what the cause might be. Thanks!

 

Hi cwerdna,

The heater is off - when the problem occurs, the engine will run whether the heater or A/C is on or off. This definitely isn't the normal behaviour you describe - as you said, the engine will run to charge the HV batter or warm the catalytic converter. However when this problem happens (not every time, but around 50% of the time I drive), the engine will run 100% of the time, no matter what the state of the battery is. I can come to a complete stop, with the battery showing full charge, and the engine will run indefinitely.

Dearler update: No error codes have been recorded and the dealer tried to say there was no issue, and it was just normal operation. I explained that I am aware of what the normal behaviour is, but that on some trips, the engine will just run 100% of the time and never shut off (until the car is powered off).

 

It's possible - is there any way to tell if this is the case? The problem comes and goes, unfortunately, so it's difficult to do testing/diagnosis.

 

Thanks F8L, I'll get this tested!

 

Frustratingly, the dealer tried to give me a lecture on how a Prius works because they could not replicate the issue. I explained to them that it's not normal for the vehicle's engine to run non-stop for an entire trip lasting over an hour. However I do understand that since they couldn't observe the problem, they couldn't do much.

There doesn't appear to be any voltage problems causing a high draw, and there are no error codes recorded.

The issue hasn't happened again since last week, so all I can do is wait. For now, it remains a mystery.

 

Hi JMD - I'm familiar with the time required to warm the catalytic converter, this incident has occurred multiple times on several long journeys. At other times, the car operates normally.

Hi F8L - It happened several times over the last 2 weeks, after both long and short trips. For example, I took a long (45 minutes) drive, the ICE was running 100% of the time. After restarting the car, the problem continued. It seemed to happen regardless of HV and 12v battery charge.

 

It looks like you folks may have been on to something! I located a plastic shopping bag that was firmly lodged against the vent, partially blocking it. Thank you all for suggesting this! I had no idea the vent was there.

I'll see if the problem goes away and report back.

 

Just a quick update - the car has behaved normally since I removed the blockage. We are expecting some hot weather this week, so it will be a good test. I'm confident the problem is solved, thank you all again.

On a related note, it's disappointing the dealer didn't think to check the HV battery ventilation after I reported this issue!