Mazda 6 2004 2.0D Turbo 136 hp - Fuel Pump A Control Circuit Low

[Codelove]

There is a Mazda 6, 2004, 2.0D Turbo, 136 hp.

It has the following two error codes:
P0088-FF Fuel rail pressure sensor circuit high input
P0628-FF Fuel Pump A Control Circuit Low

https://i.imgur.com/QPB7KLQ.png

I read that it's usually caused by corroded/defective cables in the fuel pump on this link (https://www.obd-codes.com/p0628)but this particular car uses high pressure fuel pump, which is located at the engine bay. Link (https://www.ebay.co.uk/itm/MAZDA-6-D-TS2-07-12-MK2-GH-2-0d-RF-HIGH-PRESSURE-FUEL-PUMP-RF7J13800A/353373074071?fits=Model%3AMazda6&epid=1213817992&hash=item5246ad3297:g:tVoAAOSwxGpe8MUu)of the fuel pump.

What could be causing it? There were broken fuses and relays and my father replaced them. They all work fine now. Especially the one for the fuel pump which is inside the car's fuse box. So, that's not an option anymore.

[Meat-Head]

That eBay link the bit with the wires “scv suction control valve”

Could be sticking making over pressure

[Codelove]

Thank you very much! It's good to note that some local guy took parts from another engine and put them on this one. We don't know what he did, but some of the parts are not matching. I think the fuel pump or any of its sensors are inconsistent with that engine.

[Codelove]

@Meat-Head, thanks, one of the wires was disconnected or just not in its original place, just like you mentioned above and that was causing the low voltage. Now the problem is that the voltage is high.

https://i.imgur.com/PHd4lbu.png

The following link states that the fuel pump relay is causing those issues, but we replaced it and it's still the same.

https://www.carobdcodes.com/mazda-p0629-fuel-pump-a-control-circuit-high.shtml

[Meat-Head]

Check all fuses with ignition on with test lamp
check dk thanks function, Does it have pump in t’ tank?

[Codelove]

@Meat-Head, what do you mean by "dk thanks function" and no, it doesn't have a fuel pump in the tank. There is only a high pressure pump near the engine.

Edit: all fuses are okay (in the engine bay and in the car). Just replaced the fuel pump relay and the F18 fuse with a new one. And still the same. I'm not even able to erase the error code. It doesn't let me, because it's Active https://i.imgur.com/2NudjBt.png.

Edit2: Is that normal that the values are zero'd while cranking? https://imgur.com/a/HieARSI

(https://imgur.com/a/HieARSI)https://i.imgur.com/3DtzKut.png - those values are not moving at all, not even while cranking or when the engine starts.

While cranking, the car produces strange knocking sounds.

[Meat-Head]

1) thanks button under posts (unless your on mobile site)

2) sounds like broken wire or ecu

3) knocking, maybe had entire can of easy start and bent few conrids
Or hydro locked and bent con rod

[Codelove]

@Meat-Head, which wire do you suspect?

[Meat-Head]

A) put a 501 sidelight bulb instead of the scv

B) are the pins in the plug look like they bern fingered by an elephant

[tspcrowther]

Hi,
Did you find a fix for this issue?
I`m having identical symptoms on a 2009 Mazda5 2.0D, likely a very similar if not identical engine.

Things I`ve noticed so far...
When I first got the fault code, I cleared it and it was fine for a week.
Then, whenever I cleared code, it would reappear almost immediately.
There would be some knocking until you build the revs up a bit. Idle was high at approx. 1000rpm, revs limited to approx. 2500rpm
Sometimes restarting engine would return idle to normal and no rev limit but still down on power.
If I removed and replaced the electrical connector to the what I assume is either the pump, vacuum pump or PCV valve (top right most connector, two wires...) and then reset the codes, things would appear normal again for maybe 20 miles at first, but lately a lot sooner, but they wouldn't appear straight away as when I just rest codes without doing anything.
Had a Pro round who fiddled with a few things, cleaned plugs and sockets, reset some settings etc... and got it going again for a full week no problems... Very occasional very short loss of power.. Then fault came back.

If I remove said plug and start engine, I get a boost sensor open circuit code.