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No boost and CEL after ECU change

17K views 23 replies 10 participants last post by  Aerodyn 
#1 ·
Longtime lurker, first post. 03 9-3 Arc

Had ECU replaced due to short, dreaded P0601 code.

Left dealer with CEL code P0325 knock sensor 1 circuit malfunction bank 1 or single sensor. Dealer wanted to charge me another $450 for a knock sensor that doesn't exist.

Now has codes P1351 ignition coil control circuit high voltage, P1352 ic output high/pulse detected when gnd cyl 2, p1353 same cyl. 3, and p1354 same cyl. 4.

Replaced plugs, coils and exhaust gas control (t-shaped unit on right of engine.) - all the parts I'm aware of that contribute to knock sensing. Still no boost, still same codes. Boost meter on dash shows boost going up to halfway, but I don't feel or hear anything.

Any ideas where to look next? Dealership is no use - they say the problem was there before the ECU swap and not their problem.
 
#2 ·
Sounds to me like they put the wrong ECU in?? ha but it shouldn't work at all if that were the case....

This shouldn't cause the code, but have you checked for boost leaks? Also have you tried clearing the codes and resetting the battery? Sounds like they didn't marry the ECU properly to me.
 
#3 ·
reset codes, cleared battery. Checked for vac leaks. I would think if boost control it would throw codes for that. Haven't inspected blowoff valve yet. It's got to be something related to installing the new ECU - knocked off vac line or disconnected something, but I'm at a loss.
 
#6 ·
Have you checked all of your fuses? Perhaps one was shorted out in the installation or when the ECU shorted out.

Check both boxes (cabin and under the hood)
 
#7 ·
Ehhaust ionization module-yeah, that's the thing I couldn't remember the name of...it's been replaced with a known good one.

On a whim, I took the new one off yesterday to check connections. The numbers on the new one and old aren't the same. Do the parts need to be identical? I "assumed" the dealership would order and install the correct part. Bottom in pic is new, top original
 
#9 ·
the ecu for T8 are the same,the software for the engine is loaded onto it by the dealer using TechII,as they come to the dealer unprogrammed..

i'd be going back & making sure they've loaded the right ecu software for your engine..

it's not uncommon for manufactures to change pt#
 
#12 ·
Hi, I know this is an old thread but am curious if you ever resolved the problem, and how? I have the same exact symptoms after changing the ecu on my 9-3.
What year are you? What part number came out and what went in? I think it has been solved because the wrong part number was used.
 
#20 ·
Has anything been resolved about this? I have the same problem but from a used ECU. I'm trying to figure out what ECU is compatible with my car now.

I have a 2003 Saab 9-3 Arc (Same as OP i think) and my part number is different from his original and replacement.
 
#21 ·
Hello, in my case it appears the wrong ecu was installed, I sent my ecu in and received the same part number I originally had. the cel still remains on and I still show a couple of codes P0300 and P0325 But the drivability is pretty good and no smoke, so I just learned to deal with it.
 
#22 ·
Thanks. I was able to find one that came from the exact same model as my car, different part number from my original one though, but it works perfectly now. I guess I can't use one from another year.

However, I read about SPS Programming, that is supposed to wipe the ECM completely, which should remove the previous engine software, and be reflashed to the current engine you are putting it on. But the dealership said they can't reprogram ECMs. So I don't know if they just wanted me to buy one from them for 800+ or if they truly can't. But It works now and hopefully no P0601 code.
 
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