2012 Prius C Engine noise

are you losing any coolant?

 

Report coolant level.

 

another possibility is the egr valve

 

I don't think it is the head gasket, what i think it could be even though i have not hear of it happening in the Prius C, is the heat exchanger it has neart he catalytic converter, to circulate engine coolant there to warm the engine faster, i think that could leak and let the coolant go into the exhaust.

 

Why would the VVT actuator be doing anything at all when the engine is at low and steady RPM?

Also the ECU has at least a few things watching out, ready to spring check-engine warnings for over or under-advanced cam timing.

Your car doesn't sound exactly like ours, but it didn't sound concerning to me in that clip.

 

I heard the change, I would've characterized it as valve tap. I've owned a number of cars that did similar during warmup, and it never mattered to those cars. This is largely why I say I didn't hear anything concerning.

You should see the check engine light when you turn on the ignition without proceeding to READY mode- that's a lamp test so you can be sure the indicator actually works.

You might to be able to pull codes from the car by shorting the right pins on the OBD interface. Blink code instructions. I've never tried it on a c model, so I don't know if it works the same as with the bigbody Prius.

 

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Maybe a damaged or worn-out engine mount can cause vibrations that may be mistaken for knocking or tapping sounds.

 

My guess is that some of the ECUs in a c will play along, but it's never all of them. Looking for engine codes, I don't think the ECM has ever been one of the ECUs that will blink codes, in any Prius.

You can always go short those pins one day just to see which lights on the dash blink. If the ECU has no codes for you, its light will just give a fast steady blink. So you can see, any time, which ECUs have that ability.

For codes from the ECM, the good news is, pretty much any old scan tool will show those.

 

I have the exact same issue/sound with mine at 255k km. Mine started doing this around 220k km but it didn't necessarily get worse at cold start and largely disappears once the engine is warm (or approximately 10 minutes into driving).

Over the past couple of days I have noticed a bit of a misfire when the vehicle goes through its warm up cycle when parked. Have you noticed this on yours as well? And did you end up getting this resolved?

 

Mine has been doing that for a while now at around 240,000km. There were no codes and no misfire counts but it sounded like one.
I finally replaced the PCV this morning and it seems to have gone a long way to solving the problem.

As you can see, the old one was a mess.