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Check engine light P2251 code.

Youngmustang

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So my car was idling really weird like it wanted to turn off but then the revs would go back up. So after work I checked and the check engine light is on and the Code "P2251 02 sensor Negative Current Control circuit/open". Does anybody know what the specific problem is. Can I do something on my end or should I take it to the dealership. I do have a tune, headers and CAI. So I really don't want to take it to the dealership is this a simple fix?

Update: I got 2 other codes P0030 "H02S Heater Control Circuit" and P068A "ECM/PCM Power Relay De Energized Performance- Too early". This happened after I reflashed the tune. I had the tune, headers, and CAI for over a month with no problems.
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astolt12

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So my car was idling really weird like it wanted to turn off but then the revs would go back up. So after work I checked and the check engine light is on and the Code "P2251 02 sensor Negative Current Control circuit/open". Does anybody know what the specific problem is. Can I do something on my end or should I take it to the dealership. I do have a tune, headers and CAI. So I really don't want to take it to the dealership is this a simple fix?

Update: I got 2 other codes P0030 "H02S Heater Control Circuit" and P068A "ECM/PCM Power Relay De Energized Performance- Too early". This happened after I reflashed the tune. I had the tune, headers, and CAI for over a month with no problems.
Do you have the extensions on your LTs to the HO2s?

it sounds like your O2 sensor just crapped out. Problems of having long tubes.
 
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Youngmustang

Youngmustang

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Do you have the extensions on your LTs to the HO2s?

it sounds like your O2 sensor just crapped out. Problems of having long tubes.
I don't have the extensions because I have a automatic and they reached without them. I'm going to check later today and see if everything in connected.

I only had the headers for about a month. I don't see why the sensors would stop working.
 
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Youngmustang

Youngmustang

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Anybody else got advice?
 

IowaPony

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I've got LT's as well, and I'm pretty sure one of my o2's crapped out on me. I'm waiting on the dealer, because they gave me the wrong sensor. Hopefully it's just a bad sensor. I've put about 1200 miles on since the LT's were installed. I've got 3 codes pertaining to the o2 sensor, so I'm 99% sure that's all it is. Mine runs like crap until it warms up. Engine light just bugs the shit out of me, and I don't want to clear it, because it's still in my mind.
 

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So my car was idling really weird like it wanted to turn off but then the revs would go back up. So after work I checked and the check engine light is on and the Code "P2251 02 sensor Negative Current Control circuit/open". Does anybody know what the specific problem is. Can I do something on my end or should I take it to the dealership. I do have a tune, headers and CAI. So I really don't want to take it to the dealership is this a simple fix?

Update: I got 2 other codes P0030 "H02S Heater Control Circuit" and P068A "ECM/PCM Power Relay De Energized Performance- Too early". This happened after I reflashed the tune. I had the tune, headers, and CAI for over a month with no problems.
DTC P068A is indicative of an internal PCM failure, a PCM power relay failure, or a PCM relay circuit issue. That issue can result in a lot of other DTCs and concerns.

Start by inspecting the PCM power relay to verify that it's properly seated in the junction box. I would remove it and inspect the pins; make sure none are pushed out.

If there is no visual issues with the relay, ensure that nothing aftermarket has been wired into the car. Anything that uses a circuit or connection related to the PCM power or ground can cause this issue. If no aftermarket components are installed, reflash the PCM to stock and see what happens. If the issue goes away, that confirms that it's tune related.
 

IowaPony

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Anybody else got advice?
I looked into my wiring last night and noticed that I had a set of o2 sensor wires that were too close to the headers, so they had melted together. That could very well be your case too. I pulled the wires apart and it's running a lot better now. Redoing the wiring tonight.
 

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I started seeing issues with the AFR gauge stuck at 14 a few weeks ago. I assumed it was a byproduct of the rear O2 sensor codes I was already throwing and I uploaded a new tune for the LT headers to clear it out. But I noticed the new 2251 code while I was hooking up and checking the codes again. I went ahead and changed the tune thinking it should fix the issue, but nope.

Been trying to read up on this O2 sensor and trying to see if there are solutions. I understand it may be as simple as replacing the extension harness or even swapping out for a new O2 sensor. But is there a long term solution?

Are there "better" O2 sensors to install? Something more "heavy duty?" I've seen people suggest to re-weld the bung in the collector with a tilt facing down/rearward. Not sure if that's been successful since I didn't see a lot of follow up on it. If it definitely is the sensor and not the extension, just wondering if there's another option instead of replacing with seemingly "fragile" sensors.
 

gottasrt4

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anyone have any updates? I'm having this problem, too.
 

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SR56

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I replaced the passenger side o2 sensor and it went away.
 

gottasrt4

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Very cool. I’ll hook that up. Thank you, bud!
 

RussTang

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im having the same issue and just replaced the passenger side 02 sensor and the extension still have p2251 with the afr stuck on 14. Starting to wonder if its wiring related
 

RussTang

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UPDATE: Well ive replaced o2 sensors, extensions and the pcm! STILL GETTING THE p2251 code, we checked the wiring with a meter and there is signal. im running out of patience and options. Anybody have any ideas?
 
 




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