07 prius check engine light. need to bleed the air in the coolant?

Yes. However this should not be an issue unless the car had previously been damaged and the coolant system was repaired.

Not sure whether you are asking because you plan to do the work yourself. If so, you can obtain repair manual info at techinfo.toyota.com

 

No, it is not OK. I'll give you the basic steps, but strongly suggest that you download the repair manual pages so that you have access to the same info as provided to the Toyota dealer techs.

1. What coolant currently is in the system? If anything other than the pink Toyota Super Long Life Coolant (which is premixed with water), then plan to drain out the current coolant and replace with the correct coolant.
2. The engine coolant capacity is 9 US quarts; however my experience is that after opening all three drains, only 6 US quarts will be drained. Hence a reasonable amount of old coolant is trapped in the heater core and the plumbing.
3. If you have the correct coolant in the system and only need to get rid of the air, then buy a gallon of SLLC from your local dealer, price should be around the low $20 range. Otherwise buy two gallons.
4. Make sure the car is IG-OFF. Remove the black plastic cover over the radiator. Six plastic pins hold the cover in place; use a small Philips screwdriver to twist each pin as you exert upwards pressure to release the pin from the upper radiator frame.
5. Skip to step 7 if you are just trying to get rid of the air. If you are going to drain and replace the old coolant, then locate the three drains: one in the coolant heat recovery canister (located behind the driver's side front wheel fender liner - remove the front of the liner for access.) One on the driver's side of the radiator. One on the engine block, must get under car so that the engine is over your chest and your feet sticking out by the front bumper - then you should be able to see the drain cock.
6. Remove the radiator cap, open the three drains and let the old fluid out. I suggest that you capture the old coolant in a container so that you can assess the quantity of drained fluid. Note that the coolant in the canister will be very hot, watch out so that you don't burn yourself. Close the three drains, make sure they are tight.
7. The top of the driver's side of the radiator has a valve to allow air to escape. You will need a 6 mm hex key to open that valve. Attach a vinyl hose to the vent and run the other side to the radiator cap opening. Fill the radiator. Squeeze the hoses to release air. Repeat the process until you've added as much fluid as you can without starting the engine. Note that the amount you've added so far is much less than 6 quarts.
8. Start the engine using inspection mode which forces the gasoline engine to continuously run. To do this, make the car IG-ON where the warning lights appear in the instrument panel. The car will already be in P; fully depress the accelerator pedal twice. Then shift to N and fully depress the accelerator pedal twice. Then shift to P and fully depress the accelerator pedal twice. Then depress the brake pedal and press the POWER button again to make the car READY. Note that the hybrid vehicle icon will appear in the MFD and the red triangle master warning light will come on. Do not drive the car in this condition as you could damage the transaxle.
9. As the engine is running, turn on the cabin heater temp to MAX HEAT and turn on the cabin fan to the highest speed. Keep running the engine until the thermostat opens (the top radiator hose gets hot), and you should be able to add more fluid. Continue to add coolant to the system, squeeze radiator hoses, etc until you can't add any more coolant.
10. Turn off the engine. Let it cool down. Have a beer. Add more coolant. Make sure you don't confuse the beer and the coolant.
11. Repeat 8 - 10 until you can't add any more coolant. Hopefully you've added 6 quarts of coolant after draining. Then close the air bleed valve and put the radiator cap on.
12. Drive the car around for a test drive. Make sure that no warning lights appear and no gurgling is heard from the cabin heater.
13. Make the car IG-OFF and let the engine cool down. Fill the radiator full and fill the overflow container to the full mark.
14. Keep an eye on the coolant level over the next few days as you drive the car, and top off the radiator and the overflow container as needed.
15. When you are done, the radiator level should remain full and the overflow container should be at the full mark when the engine is cold.

 

Yes, turning the car off resets the MFD into normal mode.

Note that there are two independent coolant loops in a Prius. One is for the Engine and the other cools the Inverter. Getting the air out does require patience (and several repeated attempts).

JeffD

 

Since your original post said that the check engine light came on (which is an amber light that looks like a small engine), then I assume that your problem is with the engine coolant loop, not the inverter coolant loop. If you know what DTC (diagnostic trouble code) was logged, please provide that.

If the inverter coolant loop had a problem, then you would see the master warning light (red triangle), the hybrid vehicle icon in the MFD, and possibly the ABS and traction control warning lights appear (since the result of the inverter overheating is that the voltage on the 12V DC bus will sag below normal levels.)

To check the inverter coolant loop quickly, make the car IG-ON (so that the warning lights appear in the instrument panel). Listen to the sound of the inverter coolant pump which is located near the driver's side headlamp. It should sound like an aquarium pump and you should not hear any air bubbles. Also, when you look at the coolant level in the reservoir mounted on the side of the inverter, you should see that the fluid level at the back of the reservoir is higher than the fluid in the remainder of the reservoir.

If you don't hear air bubbles and you see a step in the fluid level, then there's no need to worry about the inverter coolant for now.

 

I assume that you are looking for the air bleed valve. Look for a hole in the sheet metal that covers the radiator, towards the driver's side. There may be a sticker adjacent to the hole that indicates the purpose of the valve.

Once you find the hole, you should be able to see the 6 mm hex unless it is covered by rubber trim.

 

That's great news; congratulations on doing the job better than the body shop...

Did you drain out the old coolant and start from empty or did you just add fluid to the existing coolant?

How much fluid did you have to add?

I hope that you have continued to check the fluid level in the radiator and in the overflow container when the engine is cold, to make sure the radiator is full and the fluid is at the full mark in the overflow container.

 

DTC P1151 Coolant Heat Storage Tank means that the hot engine coolant stored in the tank is not maintaining the correct temperature. This has nothing to do with bleeding air in the tank.

That code will be logged if either of two things happen:

- the water temperature of the coolant is less than 50 degrees C (two trip detection logic)
- five hours after the Prius is IG-OFF, a soak timer activates the pump. The water temperature of the coolant has decreased more than 30 degrees C from the temperature of the stored coolant.

Therefore, I conclude that this canister is faulty. I understand the canister costs several hundred $s. It lives behind the LF fender liner. When you replace it, then you will have to perform the engine coolant bleed procedure again, as we previously discussed in this thread.

 

Hello Patrick and many thanks for these great instructions. My '07 just turned 100K miles and I am planning to change both the engine and inverter coolant. I would like to drain "all" of the engine coolant, if possible.

I see in this post, and in many others, that a good amount of engine coolant (around 3 quarts I think) remains in the heater core when you open the 3 drain cocks. My question is, can the coolant in the heater core be removed by blowing compressed air into one of the hoses leading to the heater core? Like maybe disconnect one of the hoses at the "thermos" and shoot compressed air into it so the coolant in the heater core is forced out? Either out of another hose that you would need to disconnect, or back into the engine and out the engine drain cock?

Has anyone tried this? If so, what hose(s) would you need to remove? Unfortunately, the connections at the firewall are too difficult to get to (I think) so that's why I was thinking at the thermos.

Thoughts anyone? Thank you.

 

Thanks Patrick, i did what you said and the vehicle seem to be ok now. I push it up to 90 mph on the freeway and no over heating light come up.
Just one thing and Correct me if i am wrong but i think the air bleeding valve is for cooling the electric motor, not the engine.
Thanks again

 

It is true that the inverter coolant system has an easily-seen bleed valve near the front of the inverter. In addition, the engine radiator has a valve to release air trapped at the top.

Access to this valve is via a hole in the sheet metal over the radiator, on the driver's side. You probably need to first remove the large black plastic panel covering the radiator to see this. Use a 6 mm hex socket or Allen key to open the valve. The Toyota repair manual suggests running a vinyl hose from the bleed valve nipple to the overflow container, so the overflow coolant is not wasted.

 

Hello all, I have an 07 prius that had a p1121 code, I took it to the shop and they replaced the coolant flow control valve. the next day I got a red triangle for one second then went away, then a short time later on the same trip it happened again. I took it back to the shop and they couldnt tell me why this happened. The next day im on a long trip and the red triangle came on and this time it said problem and a red thermometer came on for a couple seconds then went away. I parked the car and waited a moment then proceeded home. Could this be a result of air in my coilant system or.signs of a major problem?

 

Yes, it is likely that substantial air remains in the engine coolant loop and this must be immediately dealt with.

 

Thank you so much for sharing your knowledge. Just wondering what's the size (ID) of the house that should be attached to the radiator top bleeder? Cause it definitely is bigger than the one I used for the inverter bleeder (6mm or 1/4 ID)