Flashing Check engine light, engine running rough.

Bad spark plugs or bad coil. Check those first

 

The check engine light comes on whenever there is an emissions related fault - meaning that the car is not operating within the range where it spews an allowable amount of emissions (Volkswagen managed to cheat that by design).

Seems as though you have an intermittent engine misfire, which can be fairly difficult to troubleshoot because it can be the engine itself or the emission control system that's causing it.

The next time the check engine comes on and stays on while you're driving you should be ready to read the diagnostic trouble codes that are generated and stored. I use Torque Pro and an ELM527 bluetooth adapter on the OBDII port to constantly monitor my Prius so I can check for codes the moment any of the warning lights come on - which is not often by the way.

 

Before you go to a mechanic that you may or may not know.....read the codes that are being displayed behind the CEL.
If you don't want to pop for a a code reader you can go to a big box parts store and they will read the codes for you.
How to Read and Understand OBD Codes: 10 Steps (with Pictures)

A flashing CEL (Check Engine Light) is something serious. It usually indicates that your vehicle’s engine is misfiring, which could severely damage engine TB, and catalytic converter.
One of the faster ways to find out how much junk yards are paying for non-running cars is to continue to drive one with a flashing CEL.
It can actually be WORSE than driving while very low on oil, since that can only wreck your engine.

Good Luck!

 

Yeah just for giggles, if you haven't recently: check the oil level. And coolant reservoirs.

 

Ditto the advice about a flashing CEL. Stop driving the car as soon it is safe, you are doing damage.

 

How low was it? Everyone asked about the oil level because a high mileage G2 motor when run pretty close to dry will incur lower end bearing damage. It sometimes starts as a misfire code as the vibration in the engine confuses the decode of the camshaft and crank sensor
fpg. Unexpected response to those fpg's reflect bad response to fire command and it throws a misfire code. Another words it expects certain revolutions based on ignition. If lagging it will throw a misfire code.

Be aware the motor may be toast.

But this engine is like any other engine. May have bad cops. Pull the spark plug cops and plugs and look at the cop boot very closely in the sun for cracks.
See how corroded the spark plug well is as late model G2's may allow water to get past the seal on the windshield dam if that seal is bad allowing water to run onto the top of the motor and get in the spark plug wells. You can identify which cyl is misfiring by getting the codes read it is throwing. A bad bottom end will continuously change the cylinders it reports as misfiring which will confuse you.

Go on youtube and look up Prius Inspection as there's a certain button push scenario where you can make the engine run continuously nonstop for inspection. With engine running nonstop get under the front of the car and listen to the bottom end of the motor. Listen for knocking.
It helps if someone would push on the accelerator while braking to put the motor under load. A bad bottom end bearings will knock under load. May save you alot of time.

 

Take it to autozone and have them check it. Sounds like your code checker knows there is something wrong but is unable to let you know what it is. How old are the spark plugs? a bad plug could cause a blown coil so could have 2 problems there

 

The way we used to check it before computers was to pull each wire ( now coil) one at a time and see which coils cause change/no change in the rough running engine. Once you narrow it down you can replace the plug and coil and see if that cures the problem.

 

doesn't sound good . If it was mine I would start by changing all spark plugs. I would also consider doing a compression check in all cylinders. After the plugs I would change out the coils. I'm not sure what is involved with changing out the ECU maybe someone else can chime in on that.

I wouldn't drive it until it was fixed.

 

Sounds bad but the fact that the noise stops there on the second video makes me think its a bad cop or spark plug. There's a youtube about a Prius making the same noise and it had a bad cop. I wouldn't drive it till I fixed it though.

 

Index of /prius/Prius Info/Official Toyota Info/Repair Information/Repair Manual

You need the EM chapter - Page 25.

 

So you are saying that oil leaked from the engine up through the threads and onto the ceramic part of the plug?

 

I think the diagnosis is a leaking valve cover gasket.

 

Or a loose spark plug. Either is relatively easy to remedy.

 

I read somewhere on the PC list that a FLASHING light is caused by a misfire. As others have correctly pointed out, this is commonly plug, or coil induced, but excessive moisture in the sparkplug well was the cause in ours.