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Ask Ted Ritter Your Own Question
Ted Ritter
Ted Ritter, Toyota Master Tech
Category: Toyota
Satisfied Customers: 4182
Experience:  Toyota Master Tech, ASE Certified
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I have a 2004 Prius that I replaced the ICE water pump and

Customer Question

I have a 2004 Prius that I replaced the ICE water pump and the inverter coolant pump after the POA93 DTC. All is well in these fixes but now I am getting an intermediate triangle warning light after 5-10 miles of driving. It threw an emission DTC and I checked the fuel cap and it is not treading down to a tight seal, I have not replaced the cap yet and it is not throwing the emission DTCs . Now when the triangle warning light comes on I pull over and run a scan for DTCs and get none. I finally got to run a check when the triangle warning light was still on and not DTCs. I checked the oil and it was half way between the marks so I ruled that out. Please give me some feedback as to what to do next?
Submitted: 6 months ago.
Category: Toyota
Expert:  Ted Ritter replied 6 months ago.

Hello, thanks for posting

Do you have the actual code number for the emission DTC you mentioned?

At that time the engine light must have been on in order to get an emission control fault code. The red triangle is the hybrid system master warning light and can be turned on due to the check engine light because lack of communication between the ECM and the hybrid computer. If the master warning light turns on by itself without a check engine light then the fault is within the hybrid system only and you have to use a scan tool that can access the hybrid system or it won't show any codes. Since the check engine is not on now I assume there is no problem with the engine control system at this time. Maybe the fuel cap fixed that part for now, if the filler neck is damaged and the cap leaks the check engine light will most likely come back on after a couple of trips.

Customer: replied 6 months ago.
I didn't write down the emission DTCs but the check engine light was on when it threw the emission DTCs. My home scanner won't get into the hybrid system but it has shown the DTCs when I had problems with the other Prius' I had a p3006 code. I did a delta check of the Hybrid battery and the average was 5.2V and I know 1.2V is the limit for the battery needing re-balanced. It is not throwing the hybrid battery code. I have access to a Snap-on scanner that I can get into the hybrid system, but not for two weeks. I am not getting the check engine light at all now, just the intermediate triangle after 5-10 miles.
Expert:  Ted Ritter replied 6 months ago.

Well, intermittent problems are kind of hard to diagnose anyway, whatever it is seems to correct itself and then turn the light off. Possibly a weak cell or two in the hybrid battery if it's the original. Without a hard fault code it's hard to say.

Customer: replied 6 months ago.
I agree, they are the most difficult, I have a business refurbishing the Hybrid Batteries, I have one I am going to replace the current hybrid battery with, but aging it won't be for two weeks until I can do so. What else can throw the triangle warning light without throwing a DTC?
Expert:  Ted Ritter replied 6 months ago.

A lot of problems can trigger the triangle light, take a look at a list possible DTCs for the hybrid system, off hand I'd say about 100 or so from the hybrid batteries to the hybrid computers, powertrain, braking, cooling,etc. I believe there are about 30 or so computer systems that keep the hybrid system operating.