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CEL Several Check Engine Codes

Posted: Fri Mar 10, 2017 8:06 pm
by mittens
I decided to finally pull my gauge cluster last night to see if my speedo issues were cable related. When I got it all apart, i noticed that the bulb for the CEL wasn't there. I replaced the bulb, got the speedo cable fixed, put it all back together and started her up.

The good news: speedo fixed

The bad news: CEL was on

I connected the clip to check which code i was getting, expecting it to be 33 for the Vehicle Speed Sensor.

Turns out that there were 5 including the speed sensor

22: Knock Sensor - simple fix, buy a new sensor

23: Air Flow Sensor; abnormal voltage

24: Air Control Valve - iacv?

33: Vehicle Speed Sensor - expected

49: Air Flow Sensor; use of improper air flow sensor


I pulled the fuse for the ECU power and the negative battery terminal and let it sit over night. I was hoping that some of those codes were just old and wouldn't come back.

No luck, the CEL was back on immediately. I drove it to class and back and re checked the codes, everything was back (including the Speed Sensor code)

I'm not sure where to start. The MAF that is in the car if the factory unit AFAIK. The speedo is in working condition again, not sure why the code came back. Do I just need to bite the bullet and get a new MAF, IACV and knock sensors?

Any and all help is greatly appreciated.

TL:DR CEL codes 22, 23, 24, 33, 49..... Help

Re: CEL Several Check Engine Codes

Posted: Fri Mar 10, 2017 10:59 pm
by mike-tracy
Which codes show when you have the green and black connectors uhh connected and you drive around for a while? Plugging those both in will erase the codes and do an active check for current ones. If you don't have any current codes, it should blink 1.1.1.1.1.1.... until you restart the car with both plugs disconnected.

Re: CEL Several Check Engine Codes

Posted: Sat Mar 11, 2017 12:22 am
by mittens
I will run that check this evening and post my findings.

Re: CEL Several Check Engine Codes

Posted: Mon Mar 13, 2017 6:12 pm
by Legacy777
Use only the green connector for the active diagnostic check.

https://surrealmirage.com/subaru/engine.html

Re: CEL Several Check Engine Codes

Posted: Mon Mar 13, 2017 6:41 pm
by mittens
Ok, I ran the "D-check" as described on the surreal mirage page. No codes while I was just cruising around the neighborhood, but when I got on it, code 22 popped up.

Knock sensor replacement isn't expensive or difficult, so I'm good there.

I'm still concerned that the other codes didn't clear (or came back) after I reset the ECU, but that they didn't show up on D-check.

Could a faulty knock reading cause the other codes? Or have I just not given it enough time for them to be triggered?

EDIT: I did the ECU rest by connecting both black and green connectors, drove around and all was good. Just went out and started the car, CEL is back.

I connected the black clip and all 5 codes are back. They popped up immediately after it fired up.

Re: CEL Several Check Engine Codes

Posted: Tue Mar 14, 2017 6:05 pm
by Legacy777
Sometimes the codes do not clear if an active problem is occurring. Usually you start with the lowest code first, which is the knock sensor. Fix the knock sensor, reset the codes and see if anything comes back.

I recommend following diagnostic checks in the link below to verify that the chassis wire is still good. It is known to get brittle over time so the sensor may be ok and the wiring is not. But until you check you won't know.

https://main.experiencetherave.com/suba ... r_diag.pdf

Re: CEL Several Check Engine Codes

Posted: Sun Mar 19, 2017 7:07 pm
by wtdash
99.9% of the time I've had a Knock Sensor code w/other codes, I had to fix it first b4 addressing any others....it's easy and cheap....and frequently the KS code 'caused' the others....I don't know why.
Td