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Help diagnosing code P00C6

737 Views 22 Replies 2 Participants Last post by  TurboGT
2013 Focus ST3 153k miles.

Hey good friends, got misfiring and a blinking engine light when driving yesterday. Pulled over and didn't see the code for P00C6 until I drove to AutoZone/Home and already replaced my spark plugs.

Is this code guaranteed to be the low pressure fuel pump like so many other people say? How can I test the fuel pump otherwise?

Lots of gas comes out the exhaust and makes me smell like a go kart 馃ぃ

What are your thoughts on cutting open a hole above the tank and below the rear seats for easy access? Mostly kidding馃槀

Thanks for all the support as always!!!
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P006C is a MAP/TIP correlation

P00C6 is a rail pressure code.

Just need clarification if you typoed it or not. That changes things drastically.
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P006C is a MAP/TIP correlation

P00C6 is a rail pressure code.

Just need clarification if you typoed it or not. That changes things drastically.
Sorry my bad, I must have mixed them up when typing. Definitely meant P00C6 like in the title for the rail pressure code.
Also I did have a few other codes with P00C6 but all misfiring codes. Just adding Incase this cold narrow it down further.

P0300 - Random/Multiple Cylinder Misfire Detected
P0302 - Cylinder 2 Misfire Detected
P0303 - Cylinder 3 Misfire Detected
Key on, engine off. Bring up FRP actual as well as lowside fuel pressure (might be something like FLP or just fuel pressure, I forget). Do both of these pressures read similar amounts with the key on, engine off?
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Key on, engine off. Bring up FRP actual as well as lowside fuel pressure (might be something like FLP or just fuel pressure, I forget). Do both of these pressures read similar amounts with the key on, engine off?
Low pressure is around 20 psi while the fuel rail is around 26-30 psi
So I trust the sensors, however 30psi is definitely low.

If you bump the engine over or attempt to start, do both still read 20-30psi?
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When starting the car, the low pressure pump was running at about 110 psi. Once running after a second it was reading 78-81 psi right near the actual of 79.6 psi.

At the same time when starting the fuel rail was at 161 psi while desiring 1599.8 psi. After about 8 seconds the fuel rail pressure meets about the desired value. But while it was running the fuel rail pressure would drop or be ~500-1000 psi less than the desired value.
Well it sounds to me like the HPFP is failing. As soon as the engine fires up it should be meeting desired rail pressure, especially since lowside pressure is hitting target very quickly.

I didn't get a chance to see the log (file type is unsupported on my phone) but the info you gave is pretty concise.
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That's kind of what I was thinking as well. Going to check other bits as well

I don't think the readings are that off but could it possibly be the fuel rail sensor? I've also seen some people talk about the fuel pump driver module.

Thank you for being amazing!
Sadly not the hpfp, maybe it runs slightly better idk. Gonna do the 3 sensors and after that the lpfp. Guess I'll update again if I ever fix it or trash the car.
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Now I'm not sure what to think, the point of doing the rationality check was to rule out one of the sensors.

Both the rail and lowside sensors are moderate failure items, so I can't point you in any one direction.

The only other two rogue possibilities in my head would be an issue with the wiring or terminal tension on the HPFP control circuit, or fuel aeration from the lowside pump. Although I'd expect the latter to be accompanied with lots of lean codes.

Part numbers for the sensors are here in this thread, If you needed them still

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Changed the fuel rail sensor, no luck still, curious do you or anyone have this so called "Powertrain Control/Emissions Diagnosis (PC/ED) manual" that I keep reading about in the focus workshop manual? I can't find the code P00C6 in the workshop manual either.

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Also before I forgot I'm not sure if this is my issue but I was checking other values and Fuel Tank Pressure was reading 0 psi, not sure if that is normal.
I only have access to Alldata at work, and I already looked earlier on, they do not have any troubleshooting (or even have a listing) for this code. Otherwise I'd have been a little more helpful early on. I've based everything above on the code description, no enable criteria or code specifics.

Fuel tank pressure is the EVAP diagnostic feedback. Has nothing to do with the pressure of liquid fuel feeding the engine.
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I only have access to Alldata at work, and I already looked earlier on, they do not have any troubleshooting (or even have a listing) for this code. Otherwise I'd have been a little more helpful early on. I've based everything above on the code description, no enable criteria or code specifics.

Fuel tank pressure is the EVAP diagnostic feedback. Has nothing to do with the pressure of liquid fuel feeding the engine.
Thank you for all the info my dude, you have been more than helpful, not your fault at all that this is a weird code and Ford couldn't be bothered I guess
Day 3 of repairs...

Replaced the tank fuel pump or lpfp... Still have the misfire, I'm not sure what's going on maybe I blew it, maybe the fuel rail or injector is clogged, but I have an appointment at my local Ford tomorrow so hopefully they can figure it out. And at this point I think this is not something my amateur self can fix.

Maybe I didn't run it long enough, the car seems to be running smoother, not prone to stalling I think, and the P00C6 is becoming a "historic" code, it starts like it used to too so I'm just confused.
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Now that I'm thinking about it I wonder if you have an injector stuck open.

If it's constantly spraying fuel, it's not going to build rail pressure very easily, and will definitely misfire.

It'd be worth pulling plugs, looking for a super clean piston, and turning the key on a off a few times to run the LPFP to see if fuel is spraying into a cylinder key-on.

Wouldn't hurt to do a compression test while the plugs are out though
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Almost forgot, finally got my car back today after they didn't do anything with it for 2 days and told me at least injectors 2 and 3 are leaking gas.

So we were right in thinking my final issue or possibly whole issue was my injectors and not just the low pressure fuel pump.

Changing them myself of course because the dealer was going to charge me over 2k$ for a bunch of crap.

Thanks TurboGT for all the help again!
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You're welcome, sorry I couldn't have saved you a trip to the dealer.

Keep us posted if this takes care of it!
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