Had the code checked again and it's P1607 Engine Control Module (ECM)/Powertrain Control Module (PCM) Internal Circuit Malfunction

New one including fitting is about £750

I need to look for part no. 37820PCXG01, but if anyone has any other compatible suggestions and sites of an any reputable used ECUs (or even new ones I guess if not an arm and a leg), would be grateful to learn of them.

I read that the ECU is under the passenger side kick panel, but Honda said as mine is one of the originals, it is/might be under the passenger side dash-board. Any thoughts? Read a couple of threads about the screws being triangular and a special tool needed so I can judge that when I see it. If there's a link to a thread on replacing the ECU, including the access points for the kick panels etc, would appreciate that too. As Irvatron suggested, would like to give it a clean out first.

Still can't work out why it warms up to three bars more quickly in the freezing temps. Wondering about replacing the coolant just out of curiosity, but that could be more money going nowhere.

 

I have read of corroded edge connectors on ECUs in the past, and yes it should be under a cover under passenger feet.
Many have 'security' screws on the anchor bolts as mentioned, mine does.

As per irvatrons post:
I would disconnect the battery, then pull the edge-wise connectors out of ther ECU and take a look.
Not tried in situ, but it can be done on other cars as there is enough slack in the loom.
Inspect the cable entries for green or black corrosion at the wires, and the pins themselves for corrosion/damage.
Often the act of removing and replacing is enough to sort out high resistance connection in the blocks.

HTH - I do a fair amount of industrial electronic stuff and this is quite common with old connectors that are never disturbed.
Even see it on PC boards with gold edge connectors - yank and refit and all problems solved.
Its a free fix so worth a shot...

Steve

 

Thanks Steve.

Checked all of the connectors, pulled them out and replaced them, no apparent corrosion - will wait until next frosty morning!

 

Did you check the pins on the ECU itself?

 

Not initially. Just came from opening the plate on the silver box and the circuit board was clear. Couldn't see a removable chip and previously thought the whole box was the ecu. Is that correct?

 

I was more on about the pins on the side (that connect to the loom).

 

sorry to hijack thread but what does the air pump do

 

Removed and checked the three blocks on far edge and also the blue and white connector on the panel itself. Make sense?

 

Injects air into exhaust system on a cold start.
Its an emissions thing, helps the cat work better as when cold its having a rich mixture to deal with.

Kind of an 'exhaust gas dilution' solution

 

0*C this morning and the problem is still there, so unfortunately re-jigging and checking the plugs had no effect.

Running through the possibilities so far:

There's probably only one month or so of occasional freezing temps on the south coast to come, so I could always just put up with it and then deal with it from next winter when there will be more freezing mornings to compare with.

I don't want to make a false economy and the CEL says it's the ECU itself so a replacement is the obvious thought. Having said that, I still can't rattle out that thought of it only being at freezing point and I still can't understand why it warms up quicker in the cold - maybe something in the coolant system is actually freezing and preventing the coolant from moving until it defrosts. False economy getting the coolant changed? Don't how know much it would cost, but I guess it's not the maddest thing to replace.

Then there's the possible coolant sensor or air pump. Life ain't dull.

If the general opinion is just to go straight for the ECU, then I'll start off an ECU thread and get some ideas of new and used one.