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P0030 code

PostPosted: Wed May 03, 2017 7:12 pm
by cameron griffith
So the CEL and cruise control was flashing, found out it was the O2 sensor so I purchased a new pre-cat oxygen sensor
http://www.ebay.com.au/itm/301750331880?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT#rwid


The code is still P0030. Any help on where I can go for here?

Re: P0030 code

PostPosted: Wed May 03, 2017 7:57 pm
by Surge
Did you reset the ECU?

Did the CEL go off at least for any length of time?

Do you have a multimeter ?

Apparently you can test:
"You can check the heater for continuity between pins 3 & 4 on the connector. It should be about 5 ohms."

Quoted from here :
http://www.subaruforester.org/vbulletin ... 523?page=1


The ebay ad also mentions how to test if the O2 sensor you bought even works.

I'm guessing they mention that because they get a lot of returns.

Likely a cheaper sensor and not of good quality, possibly DOA.

Re: P0030 code

PostPosted: Wed May 03, 2017 11:19 pm
by cameron griffith
The ECU got reset and the CEL stayed off until I took it for drive around the block. I've tested it with a multi meter and it looks like it's also a faulty O2 sensor cos I am getting 0 ohms so I'm going to return it.

Is there any other option than buying one from subaru as I don't want to spend a ton :lol:

Re: P0030 code

PostPosted: Thu May 04, 2017 6:19 am
by Surge

Re: P0030 code

PostPosted: Mon Jul 17, 2023 2:11 pm
by SubaruDIY20
cameron griffith wrote:The ECU got reset and the CEL stayed off until I took it for drive around the block. I've tested it with a multi meter and it looks like it's also a faulty O2 sensor cos I am getting 0 ohms so I'm going to return it.

Is there any other option than buying one from subaru as I don't want to spend a ton :lol:


Hey Cameron,
did you end up resolving your P0030 problem? I have the exact same issue as you - CEL comes on due to P0030 code somewhat randomly (possibly on cold days). I replaced the O2 sensor, and it didn't fix the problem.

As a reminder, P0030 is a fault in the control circuit for the heater element of the O2 sensor.

This thread is from 2017, so I might start a new one if this one is cold (no pun intended).

Re: P0030 code

PostPosted: Mon Jul 17, 2023 4:42 pm
by bigBADbenny
P0030 for H4DO Legacy 2006 on jdmfsm dot info:

Wiring diagram:
https://jdmfsm.info/Auto/Japan/Subaru/L ... 04336e.pdf

Diagnostic steps:
IMG_2023-07-17-134054.png
IMG_2023-07-17-134054.png (255.78 KiB) Viewed 2404 times


Having the complete fsm pdf will be helpful: see the red link in my signature.

Don’t forget to reset the ecu after repairing the fault and or sensor…

Re: P0030 code

PostPosted: Mon Jul 17, 2023 7:05 pm
by SubaruDIY20
bigBADbenny wrote:P0030 for H4DO Legacy 2006 on jdmfsm dot info:

Wiring diagram:
https://jdmfsm.info/Auto/Japan/Subaru/L ... 04336e.pdf

Diagnostic steps:
IMG_2023-07-17-134054.png


Having the complete fsm pdf will be helpful: see the red link in my signature.

Don’t forget to reset the ecu after repairing the fault and or sensor…


Thanks bigBADbenny, I'll see how I go with this!

Re: P0030 code

PostPosted: Tue Jul 18, 2023 11:55 am
by bigBADbenny
Here’s the fsm multimeter tests for the harnesses.
https://www.dropbox.com/sh/6w38xtm9lv5y ... vPTBa?dl=0
You can also search YouTube for continuity, resistance and voltage drop tests, and how to back-probe a harness wire… “the trainer” has my favourite vids…

Re: P0030 code

PostPosted: Thu Dec 07, 2023 9:21 pm
by SubaruDIY20
bigBADbenny wrote:P0030 for H4DO Legacy 2006 on jdmfsm dot info:

Don’t forget to reset the ecu after repairing the fault and or sensor…


Is clearing the fault code using an OBDII scanner and app (Torque lite), the same has resetting the ECU?

Re: P0030 code

PostPosted: Fri Dec 08, 2023 12:57 pm
by bigBADbenny
Yes it is the same thing, generally…