Hi all,

I have a CX7 and have had multiple issues. I have some questions, but also some info that others may find useful.

Initially I got the yellow engine warning light with SCR Malfunction.
Error codes were
P2047 - redundant injector control circuit
U0442 - Invalid Data Received From ECM/PCM 'B'

I contacted Mazda and they said it's a common fault with the Ad Blue system, usually the injector has gone and cost to replace is approx £300-400.

The fault was intermittent, so I ignored it.

After a few months though the DPF light started flashing. The car went into limp mode and switched off the turbo. It got gradually worse over the next couple of days to the point it couldn't really keep above 40mph going up hill.
New error codes now:

P242f - Diesel Particulate Filter Restriction - Ash Accumulation
P2463 - Diesel Particulate Filter Restriction - Soot Accumulation

I tried the process shown here:
https://chiptuning.com.au/mazda-cx7-...n-cheat-sheet/

It worked to reset the DPF light by pressing 5 times, but the car wouldn't run the regen by pressing 2 times.
It turns out that it won't run a DPF regen when there are fault codes / engine warning light.
This is apparently why the DPF blocked up because with the engine warning light on for 3 / 4 months, it hadn't been automatically regenerating the DPF while driving.

I took the car to a tuning place and they did an ECU remap, including a removal of the SCR system from the ECU for £150.
They also did a chemical DPF clean and regen for a further £150.
I got the car back and all lights now off and car runs fine. The car shows Ad Blue is full and apparently will now always show that.
I had the choice of power or economy remap. I went for economy. The car used to average 36 MPG, now averages 42-43 MPG.

Now my question:
I checked the error codes again and it still shows the code P2047 - redundant injector control circuit.
There is no engine warning light, just the code. I've reset it a number of times but it comes straight back up.
It's not actually causing an issue right now, but, I am wondering if it will stop the car running the self clean of the DPF whilst driving.

I have a new Mazda 6 also. The computer in that shows a MPG graph. I can watch it and tell when the car is doing a DPF clean because the MPG will drop from 55-65 range on motorways down to around 25-35.
It does this every 170 miles or so.

The CX7 doesn't have this facility, just an average MPG and a instant MPG counter.
I haven't noticed it dropping off a cliff like it does with the Mazda 6 but I don't know if the CX7 does it in the same way.
Does anyone know if the MPG should drop when doing a regen, and if so, how often?
If not, how can I tell that the car is cleaning the DPF or not?

Lastly, I re-tried to run a DPF clean now that the engine warning light is off, but it still doesn't work.
Should it work when the DPF light isn't flashing?
Does anyone have a CX7 that could try the process shown in the link above (it takes about 5 minutes) to set the forced regen going, see if it works and let me know?

 

DTC P2047:11

DTC P2047:12

DTC P2047:13

DTC P2047:14

DTC P2047:15

Urea injector valve circuit malfunction (short to ground/short to power supply and open)

DETECTION CONDITION • The SCR control unit monitors the input signal from the urea injector valve when the ignition is switched ON. The SCR control unit determines that there is a malfunction in the urea injector.
Monitoring condition― Following conditions are met:• Battery voltage: 9—16 VDiagnostic support note
• The MIL/SCR warning light illuminates if the SCR control unit detects the above malfunction condition in first drive cycle.
• PENDING CODE is available if the SCR control unit detects the above malfunction condition during the first drive cycle.
• FREEZE FRAME DATA (mode2) and snapshot data are available.
• The DTC is stored in the SCR control unit memory.

POSSIBLE CAUSE
• Urea injector short cord connector or terminal malfunction
• Urea injector malfunction
• Short to power supply in wiring harness between urea injector short cord terminal A and SCR control unit terminal 74
• Short to power supply in wiring harness between urea injector short cord terminal B and SCR control unit terminal 91
• Short to ground in the wiring harness between urea injector short cord terminal A and SCR control unit terminal 74
• Short to ground in the wiring harness between urea injector short cord terminal B and SCR control unit terminal 91
• Open circuit in the wiring harness between urea injector short cord terminal A and SCR control unit terminal 74
• Open circuit in the wiring harness between urea injector short cord terminal B and SCR control unit terminal 91
• SCR control unit connector or terminal malfunction
• Urea injector connector or terminal malfunction
• SCR control unit malfunction