Is my ecu fried
 

Hi all, 99 wrx with sti engine .i very stupidly reconnected my battery while ignition is on and now i have some gremlins. Car runs ok but now throwing an o2 sensor code. Sensor was just teplaced. Also speedo now works sometimes, jumps wildly sometimes and mimics the tacho at others times. Car runs fine sometimes but crap other times. Boost is also slightly down. Max 13psi. Have i fried ecu.

just replacing sensors wont erase the CEL code . You need to reset the ecu by joining the test and reset plugs under the drivers side near the steering column. Might also be a good idea to disconnect the battery for a good 30 minutes and let the ecu do a hard reset by letting it fully discharge.

But ecu must be test and reset after replacing or fixing code items .. Search the site for Green and Black plugs and ecu should be enough keywords to bring up pages of how to do it mate.

Sorry i was in a hurry when i posted. O2 sensor had been in for a few weeks. Car was going ok. Had battery disconnected to charge. When i reconnected it the ignition was on and now i have the above problems. I have reset ecu 5-6 times both by battery and connectors under dash. Problems slowly getting worse. Bot sure if its ecu or sensors but definateky caused by connecting battery while ignition on.

Nah connecting bat while ign on won't hurt anything.

WRX or STI ECU? or aftermarket?

Jdm Sti ecu.

Bugger, I just sold one for $150

There is another on Gumtree at the moment, but the seller is asking for $350 which is too much in my opinion.

That's if you need to replace the ECU...

I tried replacing instrument cluster this arvo. No change.

Maybe ask the guy if he will drop his price or even ask of you can test it to confirm 100% that its the issue

Still having issue with the tacho. Last time i had this issue was the vehicle speed sensor with the speedo not working properly and couldn't rev pass 4.5krpm


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Jadyn samelko on sowa was selling two sti ecus tested ok. It was around 100 bucks.


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Matto20v don't forget me please.


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Ive taken it into an auto elec. They said its just a bad earth. They have had car for 2 days now and still not fixed. Scared they are going to charge an arm and leg.

All sorted. Turned out was bad earth under coil pac.

Try changing the cam angel sensor as this affects the engine at about 4K when it falts some times