Code P0508 will not go away

2004 JEEP LIBERTY

105,000 MILES • 3.7L • 4 CYL • 4WD • AUTOMATIC

LAKEHILT

MEMBER
4 POSTS
FOLLOW

Been getting a code for Idle Air control circuit low- P0508 on my vehicle. IAC was changed and rewired along with the PCM being changed, throttle body was cleaned and changed TPS. Code was cleared ran great for 5 days then code reappeared along with a whistling noise and it doesn’t want to start sometimes so I have to disconnect battery and it will start after. Running out of options because after all that it still isn’t fixed. Need help as I can’t afford to take it to a mechanic. please help!

Nov 22, 2019 at 10:11 AM

KASEKENNY

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18,907 POSTS

Here is the testing for this code. I understand it appears you covered everything but clearly we are missing something.

Let's run through this test and see what turns up. Depending on the wiring that you did I suspect there is a connection issue.

Images (Click to enlarge)

Nov 22, 2019 at 5:37 PM

LAKEHILT

MEMBER
4 POSTS

Will run through test today and get back to you. Thanks!

Nov 23, 2019 at 6:43 AM

STEVE W.

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15,113 POSTS

Check for a vacuum leak as well, a whistling noise would be what a leak would indicate. A quick spray of starting fluid or carburetor cleaner would help track it down.

Nov 23, 2019 at 7:35 AM

LAKEHILT

MEMBER
4 POSTS

Thanks Steve, will check for that as well!

Nov 23, 2019 at 8:10 AM

LAKEHILT

MEMBER
4 POSTS

Did all checks on IAC and also checked for vacuum leaks. There is no issue with either. I checked fuel pressure and it’s high around 62 PSI looking like I need a new fuel pressure regulator. Could this have caused the IAC code?

Nov 23, 2019 at 10:55 AM

KASEKENNY

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18,907 POSTS

Assuming you have a JTEC controller then you are correct that it is a bit high.

However, that is highly unlikely that it caused the IAC code. Do you have a scan tool to see what the MAP is reading?

Image (Click to enlarge)

Nov 23, 2019 at 8:03 PM