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Discussion Starter #1 (Edited)
2003 Disco 2
130k miles
4.6l V8

I've been chasing down the P1412 issue for a month. Here is what I've done so far:

  • Replaced the SAI Pump with a new unit. It howls as it should upon start up for 70-80 seconds
  • Replaced, twice, the Solenoid on the Drivers side
  • Checked, re-checked, and then checked again all the vacuum hoses, big ones and small ones. They are all secure.
  • I bough small clamps and placed on all the vacuum hose ends to ensure there was no leak.

As soon as I start up, I get a pending 1412 code followed then by a CEL light with the official P1412 as a stored fault code. I can clear it but upon a cold start its back again.

Strangely, my SAI pump is coming on at idle way after the truck is warmed up which is why I tried the second, replacement solenoid.

Any other suggestions? Maybe the Vacuum Reservoir? Maybe Valve Air Control ?

Any thoughts otherwise before I sink more $$$ in?

Thank you.
 

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In the emission control section of te workshop manual there is a chapter " Fault finding and check malfunctions" where it's described how to test each component according to the faut code, IMO you should check the valve as described there before you spend money on it cos it can be a wiring issue while the valve is OK

"
 

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Discussion Starter #3
Thanks Fery as always. I had some time today and attempted to take the valve off but as luck would have it the bolts are both seized and feels as if Im about to snap them off. Soaking now with PB Blaster. I didnt see any obvious wiring flaws. Nothing melted nor frayed. Everything connected and firmly in place.

That said I poked around more and as per your direction I followed the following:

Flow Fault Finding chart
1 Fault codes P1412, P1414, P1415 or P1417 present
2 Insufficient flow detected
3 Is fault present on both cylinder banks?
If 'NO' proceed to step 4
If 'YES' proceed to step 8
4 Vacuum supply – Check for: blockage and/or vacuum line disconnected from SAI valve
5 SAI Valve–Checkfor:jam/diaphragm leak or blockage
6 Delivery Hoses to SAI Valve – Check for: blockage / leaks
7 SAI Pipes to Cylinder Head – Check for: blockage / leaks
8 Electrical Issue – Check for: Related P code (relay/fuse/solenoid), rectify as necessary and check connectors
9 Vacuum Supply – Check for: Blocked/leaking vacuum lines or correct solenoid operation (open/closed)
10 Delivery Hoses – Check for: Blocked/leaking hoses
11 SAI Pump – Check for: Correct operation using TestBook/T4 or pump blockage/failure

12 SAI Valves–Checkfor:BothSAIValvesjammed/blocked/leaking diaphragms

Question- can I spray carb or throttle body cleaner (or the like) in to that valve to clean it up in some way? Sorry my knowledge is nill on these valves as I have no idea whats inside them.

Once I can manage the bolts off the bottom I can investigate internally more so but until then has anyone any luck with a mechanic in a can approach on these?
 

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That Flow Fault Finding Chart is very well explained especially when you can troubleshoot just the LH side for a fault.

From the RAVE manual... P1412 - SAI system fault (LH side) - air delivery not reaching catalysts. That fault code sounds like the LH SAI control valve isn't actuating which allows SAI pump air to be sensed by the upstream and downstream O2 sensors (B1S1 & B1S2).

Yes you can spray carb cleaner into the SAI vacuum solenoid valve. But remember... the valve is supposed to be closed when not energized so you will get a face full of carb cleaner when you spray it into the tiny passage ways.
If the valve is good, I'd really check the rubber vacuum line boot to the LH side SAI control valve for leaks.
 

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Discussion Starter #5
Mike and Fery - Thanks for the input! The resolution on this was a faulty SAI Valve on the drivers side. Fortunately the replacement unit also included the 10mm bolts needed because when attempting to remove the old valve, the bolts both sheared off, even after a couple days of PB Blaster. I also noted the little "nubs" that screw into the heads from the down-pipes from that valve were a little loose.

Cheers!

92581
 

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(y) well done, i'm glad you are sorted
 
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