Just for kicks, I hooked up my Equus 3160 scan tool to my 2007 Prius with 76,000 miles to read some live data - no check engine or any other service lights are illuminated - and sure enough, it revealed that I do in fact have a DTC stored! It says "P0203 - Cylinder 3 injector malfunction- circuit open or short" The car seems to be running very well in spite of the DTC and I have been getting ample mpg's (no noticeable decrease other than from winter fuels/winter temps). Does this mean I have to replace my #3 cylinder fuel injector? Any guidance is appreciated!
The causes of a P0203 engine light code could be a bad injector. This is usually the cause of this code but doesn't rule out the possibility of one of the other causes...open in the wiring to the injector Use a DVOM check the resistance of the injector. If it isn't within specs, then replace the injector. Check for voltage at the fuel injector connector. It should have 10 volts or more. Visually check the connector for damage or broken wires. If you have access to an injector tester, activate the injector and see if it operates. If the injector operates, then you likely have either an open in the wiring, or a blocked injector. If you do not have access to a tester, swap the injector with another one and see if the code changes. If the code changes, then change the injector.
This could be a transient situation, not presently active. It could also be a false positive. There are enough examples here of generic code readers giving random DTC that are not duplicated when using one of the Prius specific units.
I do have techstream software, I just didnt have it on me at the time. Now that Im home, I have to reset my TPMS anyways for my winter tires with Techstream, so Im going to check out the DTC with that too while Im at it. Ill report back...
Hmmm ok very interesting... I went outside with my laptop that my Techstream software is on and the OBD2 cable. Programmed my winter tire TPMS ID's and turned off my TPMS light. Checked for DTC's in every category and nothing!! Unplug the Techstream, plug in the generic Equus 3160, it says P0203 again under the enhanced codes. Im going to take what you said and run with it! lol.
OK. This is just another data point against generic readers and the Prius. It is all too typical, where what is initially set forth as a industry wide standard becomes more and more elaborated over the years, until the backwards compatibility is broken, and things devolve into de facto proprietary protocols. Just look at the process of websites that work with some, but not all, browsers over the years. How nice not to be fiddling with the engine in freezing conditions.
Im going to go OT, but thats ok because I created this thread But programming my winter tire TPMS sensor ID's for the first time with Techstream was SOOOO easy. I thought it'd be more complicated. I also enjoy looking at my hybrid battery cell block voltages, and fun nerdy stuff like that. Fun nerdy stuff my Equus couldnt do on its best day...
The Mini VCI with Techstream is a great piece of kit. Even using it just for TPMS makes it worthy of purchase, and it works with nearly all Toyota's, and Lexus. John (Britprius)
