CHS related CEL question

First off the information on this forum has been great Our 2005 prius has logged 170,000 miles (we purchased it used with 90,000) and this is the first time we've ever ran into any issues with it, love the car. Well, a few weeks ago the check engine light came on and we just happened to have an emissions inspection that week, which was failed because the check engine light was on (they didn't even test the exhaust).

After taking it to a local dealer to see what the check engine light was all about, they came back and told us it was related to the Coolant Heat Storage system and that the CHS temperature sensor would need to be replaced. They also told us that the water pump had a minor leak and would need to be replaced. Another non-related but related issue is that the driver side wheel liner was ripped out when my wife decided some off-roading... and after seeing where the CHS is located this might be a factor.

Could low coolant levels (related to the water pump leak) be causing the CHS temp sensor alarm? I'm making an appointment with the dealer to have water pump replaced (or may DIY if the job isn't too bad), I'm just wondering if I should hold off on the CHS related parts until that has been fixed. I checked all the connections and everything seems good, no corrosion yet. The temp sensor is on the front side of the tank so it wouldnt be getting splashed too much by the wheel even without the liner.

I did also get a new fender liner but don't have the plastic push pins to put it in. Anyone know what the part number is for those, or if there is an install kit?

 

I also noticed when turning on/off the car I can't hear/feel any noise from the chs pump, and the lines to the pump are cold even when the car has been driven for awhile. If the pump was out would the temp sensor be faulting?

 

Hi guys, thanks for the reply.

There is a 2nd water pump that was replaced while they did the inspection under a recent service bulletin, forgot the name of it but it's wasn't the water pump attached to the engine (the one currently leaking).

I considered doing the water pump myself but all the documents I find refer to a special tool for the pump pulley, which looks to be $400+.. Is it possible to be done without the tool (SST 09960-10010)? The dealer quoted around $550 for the the labor/water pump/coolant and a new belt.

As for the CHS, the pump looks pretty easy to DIY, just don't want to waste $130 bucks on it till I'm sure.

 

Sounds like I better free up the weekend

 

We'll I replaced the water pump 2 weeks ago and bled all the air I could out of the driver side radiator port. Reset the codes and still have the same thing, so I just kept bleeding it every few days until there were no more air bubbles. Reset it again and same thing, so not sure where to go from here.

Downside is now the registration is expired and I can't renew it until it has passed emissions, and of course got a ticket for expired registration. So now I have about 2 weeks to get all the codes cleared so I can pass emissions and get new stickers before court

Can't believe all this trouble just because our prius can't pass emissions lol..

On a side note I was able to replace the pump without the SST, but the belt wasn't able to hold the pully on its own. I ended up running some heavy gage wire through the pully and a hole on the engine block to keep it from moving. Would have been a quick job had I not snapped one of the studs because of my cheap torque wrench, so ended up spending a few days getting that fixed.

 

I did not drain the CHS tank, though I did follow Patrick's steps for testing the relay here. I didn't do a full coolant refill because I didn't believe it would resolve the issue without running the chs pump while filling and I saw some concern over a possible issue with the control valve. I'm fine with doing a full system flush as I have about 7 gallons of the Toyota coolant, just point me there

I've ran the heater at max hot and do not hear any noises. Air gets hot pretty quickly as well.

I inspected the harness and wires to see if there was any damage and it looked pretty clean, but I agree it is probably related to air in the tank and I'm just not bleeding it right. When my Wife gets home from work I'll drain some coolant from the tank and see what the temp looks like.

 

Was able to drain some coolant from the tank today and its ice cold. Pump sounds like its running fine, so looking at possibly the coolant control valve?

 

Wouldn't it log a P1121/valve position stuck code though?

 

P1116 and P1118. I ordered the valve anyway since it was only 60 bucks at toyotaworld, I'll swap it out next weekend and bleed the system again, hopefully all will be good.

 

I did have a P0137 as well, which replacing the o2 didn't resolve so this is interesting. Though it still wouldn't explain why the coolant in the tank is cold unless both issues are happening. Where is the E2 ground point located or how can I test it?

Unless the temp sensor actually is bad and is what's causing the ground fault creating the o2 code as well.