2007 Prius stalled and won't start - Dealer is going to replace the computer

[ghanashyamjoshi]

Guys,

This is my first post to the forum. I have a 2007 Prius with 99K miles on it. Last weekend, I took my car for an oil change and while driving home after the oil change and air filter + cabin air filter change, my car stalled. I had to get my car towed home and then to the dealership yesterday.

I called the oil change place to see if they know what may have caused the stall - they recommended that I check the engine air filter and see if the seal was in place - I tried this but still when I start the car, it just goes in "N" with all the fault lights turned on - So, I had to get it towed to the Toyota dealership.

I told the dealer that I had done the oil change and while driving my car stalled and will not start now. After an initial check, the Service Rep is saying that he was not able to complete the diagnostics as the diagnostics is giving a code that car computer is bad - and he wants to replace it to continue the diagnostics – the Service Rep has given me an estimate of $1200 to change the computer - I don't have an extended warrantee

Do you have any ideas - is this something any of you have seen before? I have searched to find 2004 Prius had this issue but not seen anything other than 12V battery problem for 2007 Prius – my 12V battery seems to be okay as I was able to operate the keyless entry and Navigation etc just the Car does not shift in “D” or “R”.

Is my car dealership on the right track to solving the problem?

Are there things that I can ask them to make sure that I get it repaired without being ripped off?

I would really appreciate any pointers in this regard.

Thanks,
-Ghanashyam

[firepa63]

Is your 12v battery the original? It's possible that it is going bad.

[ghanashyamjoshi]

Originally Posted by firepa63

Is your 12v battery the original? It's possible that it is going bad.

Yes, I never had any major problems so far.

[Patrick Wong]

Originally Posted by ghanashyamjoshi

...I told the dealer that I had done the oil change and while driving my car stalled and will not start now. After an initial check, the Service Rep is saying that he was not able to complete the diagnostics as the diagnostics is giving a code that car computer is bad - and he wants to replace it to continue the diagnostics – the Service Rep has given me an estimate of $1200 to change the computer - I don't have an extended warrantee ... Are there things that I can ask them to make sure that I get it repaired without being ripped off?

It's hard for us to comment without knowing what DTC (diagnostic trouble code) was logged by your car. I suggest you ask for this.

The DTC code has the following format: A#### where A is an alphabet character, typically P, C, or B. # is a hexadecimal character, 0 - 9 and A - F.

In general, it is very unusual to come across a situation where an ECU has to be replaced unless some abuse happened such as accident damage or incorrect jump procedure.

[ghanashyamjoshi]

Thanks for your response.

I didn't have any such incident that would cause a damage - I just drive it a lot 30-35K Miles/Year

Got the following codes from the dealer
P040F - Failed to Start "ECM need to start with ECM"
B3193 - Failed to Run
P3190 - Poor Engine power
P171

Do you think $1100-1200 is a correct quote for replacing ECU?

[Mr.Vanvandenburg]

You are in CA, make sure you are still not covered by the extended emissions warranty. I don't have my book handy, but I believe the ecu may be still covered at 99K. Like others said, ecu's are reliable once in use. On "normal" cars it is usually possible to reset the main ecu by disconnecting the battery, sometimes it takes an hour. On the 07 II, not sure what needs to be done to reset all the ecus or if it is possible even.

I would be suspicious of the diagnosis, and make sure it is the problem and not something else caused by the oil change shop. The air filter idea sounds odd, even if the filter is not there, there are no sensors telling it isn't. It may be grossly overfilled with oil, or some other blunder like pulling a connector off.

[Mike Dimmick]

Originally Posted by ghanashyamjoshi

Thanks for your response.

I didn't have any such incident that would cause a damage - I just drive it a lot 30-35K Miles/Year

Got the following codes from the dealer
P040F - Failed to Start "ECM need to start with ECM"
B3193 - Failed to Run
P3190 - Poor Engine power
P171

Do you think $1100-1200 is a correct quote for replacing ECU?

Much more likely to be P0A0F, P3193, P3190, P0171. There is no code P040F or B3193.

P0A0F is reported by the HV ECU and indicates an engine start problem reported by the ECM, so check the ECM codes. P3190 is Poor Engine Power, P3193 is Fuel Ran Out, P0171 is System Too Lean (Fuel Trim).

I'd start by filling the tank. If the engine still won't start, then investigate air leakages or blockages - make sure that engine air filter is properly installed.

The full diagnostic tree before reaching the 'I dunno' step - replacing the ECM - is quite long. Um, posting the whole P3190/P3191/P3193 section is fair use, right? See the attached PDF.

[brick]

This is just idle speculation, but what would happen if the technician disconnected something like the MAF cable or the throttle control cable? I imagine that would play havoc with the engine. But would the ECU be smart enough to know that those components were at fault? Or would it just throw these codes which indicate that the engine isn't running properly?

[Patrick Wong]

I agree with Mike's suggestions. After that is done, if the engine ECU is still found to be at fault, I would ask the tech whether it is reasonable to reflash the ECU with the latest firmware first, rather than replace the ECU?

If the MAF was disconnected a DTC should be logged. The electronic throttle also has DTC related to it.

[richard schumacher]

Start with the simple gross stuff: check the oil level yourself. I would not even assume that the dealer has done this. What is the level now?

General good advice: always, always, check the oil level yourself before driving away from every oil change, no matter who did it.