Toyota Prius Help Log: P0607 Control Module Performance

Trouble codes on modern vehicles can sometimes be a huge pain, especially if you live in a state that requires smog testing. To make matters worse, cars are far more complicated than they have ever been. Dealing with electrical issues on a hybrid is a whole different level.

Luckily for Toyota Prius drivers, the engineers who made your car did just a good enough job to get the help we need and get back on the road, usually for cheap.

I had a reader write in and ask me about a P0607 trouble code that keeps coming back on his vehicle. As always, I had to investigate. The only downside is I do not have the car in front of me to work with, so theory right now will have to make do.

What Causes A P0607 Trouble Code?
I used my subscription to Mitchell Prodemand to see the trouble areas with this specific code to do quick work. What I found out was shocking.

I have included a screenshot to see it for yourself, but there are only three vague explanations of how this code can come about. For me, I always pick the route that makes the most sense and work from there.

• Exhaust Leak
• Heated Oxygen Sensor
• ECM

Logic tells me that a Prius between 5 and 10 years old is likely to have an exhaust leak. Because on Gen 3 Prius with the 1.8L engine, the donut gasket between the exhaust manifold and downpipe is prone to deterioration.

I have fixed these gaskets on multiple cars with exhaust leaks. Some of them with trouble codes (not related), others without trouble codes but noisy.

My first course of action would undoubtedly be to thoroughly examine the exhaust system and check for any signs of leaking pre-oxygen sensor.

Post oxygen sensor leaks will not cause a check engine light as there is no sensing system.

Checking The Oxygen Sensor
If there are no exhaust leaks, I would question the integrity of the oxygen sensor. It is designed to sense how much oxygen is being stored in the converter.

This sensor is not to be confused with an air-fuel ratio sensor which monitors the amount of air/fuel in the exhaust gasses pre-cat converter.

Pro demand specifically states "Heated Oxygen Sensor" it would be best to check that one and not the A/F sensor.

The ECM
To computers break? Yes, they can, but the likely hood is minimal, meaning that there are typically other issues causing the trouble code. An ECM is a costly replacement, and you had better be certain.

Checking and ECM can sometimes be as simple as looking for a technical service bulletin issued by Toyota or taking a look directly at the computer and checking all the connections.

The wiring that goes to the computer can sometimes have corrosion. Any unwanted resistance in a circuit is grounds for a mountain of issues. In these moments, most technicians want to scream. Me, I take massive action.

There is always a solution to every problem we face, and an ECM is no different. Like anything electrical, check the specs and measure with a known good DMM.

If the ECU is suspect, check again and verify. Once you know for sure (trust your gut, too), then pull the trigger and replace it.

Conclusion
The simplest way to solve strangely (and random) issues like a P0607 is to start at the easiest checkpoints.

My theory for my friend with this code on his 3rd generation Prius would be to check that darn flange gasket and replace it if it is damaged. Check all the exhaust piping from there and ensure there are no leaks pre-sensor.

If that does not work, dig into the other systems. Checking the O2 sensor first before replacing it will give you a base to work from.

If and only if you are sure the ECU is at fault, replace it. I highly doubt it, but you will not know until you have tested it.

If you have any strange questions or need help in any way, let me know. I am always happy to help out where I can.

Have a great weekend, everyone, and remember, Today's Adventure is Tomorrow's Story.

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Peter Neilson is an automotive consultant specializing in electric cars and hybrid battery technologies. He holds a Bachelor of Science in Automotive Service Technology from Weber State University. Peter can be reached on Linkedin and you can tweet him at The_hybrid_guy on Twitter. Find his page on Facebook at Certified Auto Consulting. Read more of Peter's stories at Toyota news coverage on Torque News. Search Toyota Prius Torque News for more in depth Prius coverage from our reporter.