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p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control)


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completelyhis
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Jul 28, 2010, 3:15 PM

Post #1 of 16 (21240 views)
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  post locked   p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control)  

1997 Geo Prism, 1.6 liter, 175k miles.

I get a P0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control). I have changed the temperature sensor, thermostat, checked coolant level, repaired the exhaust lead that was @ the doughnut flange, and then replaced the front o2 sensor.

The engine gets to "normal" operating temperature w/in a normal time (a few minutes). It runs great. When I clear the code, it comes back within 10 miles or less after clearing it.

I read this here
link deleted............. not allowed

I know that the drive train for the prism is a toyota drive train, so that conversation is relavent, but I don't see a solution I haven't tried.

Any suggestions?

Thanks,

Ian

(This post was edited by Hammer Time on Jul 28, 2010, 3:22 PM)


Hammer Time
Ultimate Carjunky / Moderator
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Jul 28, 2010, 3:24 PM

Post #2 of 16 (21221 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

You really need a scan tool so you can monitor what temp the computer is seeing and you can then determine if and where the problem is.




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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



completelyhis
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Jul 28, 2010, 3:49 PM

Post #3 of 16 (21214 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

i assume that's different than my "auto xray" code reader? Can you recommend a good scan tool?


Hammer Time
Ultimate Carjunky / Moderator
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Jul 28, 2010, 4:03 PM

Post #4 of 16 (21209 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

Yours may work. I'm not familiar with it. You just need something capable of displaying the digital coolant temp reading coming from the sensor.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Sidom
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Jul 28, 2010, 11:05 PM

Post #5 of 16 (21200 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

I think HT is right and it's going to be a temp sensor problem...... Most of the time with this code you have a stuck open T stat. If this code is setting within 10 minutes during this time of the year, it would have to be a electrical problem.

How's it run? Any black smoke out the back or hard starting????






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completelyhis
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Jul 29, 2010, 8:57 AM

Post #6 of 16 (21189 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

no smoke, starts great runs solid and strong. replaced Tstat and temp sensor. I replaced the one that's on the thermostat housing, with a two-wire harness connected to it...is that the right one?

electrical problem...could you elaborate?

Ian


Tom Greenleaf
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Jul 29, 2010, 10:24 AM

Post #7 of 16 (21185 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

You can OHM test CTS and should show that it changes as engine warms up. I don't have the range but most are fine or do nothing. The plug can be the problem,

T
_________________________________________
Long retired now


Hammer Time
Ultimate Carjunky / Moderator
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Jul 29, 2010, 10:39 AM

Post #8 of 16 (21179 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

I think your wasting your time with those types of tests. The code here is indicating that there is insufficient temp for closed loop. I have had to deal with this code before. This can come down to a matter of just a couple degrees so unless you see the exact digital temp that the computer is seeing, your not going to solve this problem. I had one that continuously failed emission but never set any codes and it turned out to be the calibration of the thermostat. It was only about 5 degrees low but that was enough to prevent it from going into closed loop and in turn made it fail emissions.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



completelyhis
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Aug 7, 2010, 1:33 PM

Post #9 of 16 (21144 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

I took the car to a guy who has the ability to read the ECM data and it ends up that the computer is reading zero's from the o2 sensor.

i did some research and found these suggestions:

Verify continuity between the ECM and O2 Sensor
Make sure that there is 12 V making it to the O2 sensor
Check the resistance of the sensor (should be between 11 and 17 Ohms).
Are those good things to check? Any other testing I could/should do? I assume it's either bad wiring or a bad ECM. Is that a safe assumption? Where is the ECM on the 97 prism, so I can check continuity between it and the o2 sensor? Is there any reason to check the resistance of the sensor other than confirming if the sensor is good or not?

Thanks,

Ian


Hammer Time
Ultimate Carjunky / Moderator
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Aug 7, 2010, 2:56 PM

Post #10 of 16 (21133 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

That has nothing to do with the code you are getting. I actually find that hard to believe since you don't have any lean codes.




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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Sidom
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Aug 7, 2010, 3:55 PM

Post #11 of 16 (21123 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

You are little off base here with the code you are getting...

Your O2 data is way off base but since it's not related to the code there is really no sense going into this right now...

The code you posted is for an engine that is running too cool. Computer controlled engines require a minimum of 195° for peak performance. It's to the point now that and OBD II systems will actually set a code if it runs too cool after going into closed loop.

The usual problem for this code is a stuck open T stat.

You've changed it and even with an AM non-OE stat I would find it highly unlikely that the new aftermarket one is defective and sticking open as well. So the next thing to check would be the ECT (coolant temp) sensor and reading the PCM is getting.

With the scanner the 1st thing you will want to do is look at the ECT PID and see if the temp is correct for how hot the engine is or wait until the morning and look at it and the temp should be very close to the ambient temp. So is it's 70 out & temp is showing 30° then you found your problem. If not it gets a little harder, you'll need to access the freeze frame data, find out when the code set & try and duplicate the conditions......

Honestly, for a DIYer with minimal tools, you could change the T stat and then ECT sensor and connecter, if you are still getting the same code it would probably be best to take the car into a shop to have checked out....But if you have the experience to trace a possible intermittent voltage drop/short/ open in the wiring then that would be the next step before condemning the PCM.......






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completelyhis
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Aug 7, 2010, 4:04 PM

Post #12 of 16 (21120 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

I looked at the device he had hooked up to it while it was hooked up, i saw the MAF readings and all the other ones updating in real time. the o2 was zero constantly. i trust him.

Following are things I've seen about the Toyota obdII codes as it pertains to this:

  • I think that I remember Toyota mis-defining that code number. It's supposed to refer to the O32 sensor signal or heater or the sensor itself. I think I remember that from somewhere that Toyota mis reads that code.
  • By accident I left coolant temperature sensor disconnected. It generated 2 codes. p0115 and p0125. P0115 is the temperature coolant sensor. P0125 Has to do with not getting into a closed loop circuit. Auto Zone listed the cure for the code (125) as faulty temp. sensor, 2. bad thermostat or3. low on coolant. When I rewired the O2 sensor the Mil went out, no more codes,
    From my experience on a Toyota P0125 was a disconnected or bad O2 sensor. Before cat. converter. Code p0115 is disconnected or bad coolant temperature sensor. Not the sensor that controls temp. gauge on dash but sensor that controls fuel mixture. It has a plug with 2 wires connecting. The temp. gauge sensor has one wire,and it is located on the end of the engine very close to the distributor. The coolant temp. sensor is located on the firewall side of the head also close to the distributor but it faces at a right angle to the distributor.
  • I have exactly the same behavior with a 2000 Corolla. If I unplug the oxygen sensor, a few minutes later, I get a P0125 Insufficient Coolant Temperature... followed shortly by a P0135 O2 Heater Circuit.... The latter makes sense, the former, not so much. Apparently a bug in Toyota's software.
  • on some models, Toyota does not adhere to the SAE standard definition for DTC P0125. That code can be for a Coolant Temperature Sensor concern, but it can also relate to O2 sensor function... which would make more sense that a P0135 would follow.
    Fault trace the O2 sensors and if the PCM and harness check out, replace the sensor(s) with O.E. parts.


I'm not trying to be confrontational - just trying to figure the darned thing out!

Ian


Hammer Time
Ultimate Carjunky / Moderator
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Aug 7, 2010, 4:21 PM

Post #13 of 16 (21113 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

You know, this is my fault for just taking your word for the definition of this code number. After looking into the code, it appears that it has nothing at all to do with coolant temp.
P0125




CIRCUIT DESCRIPTION
The Oxygen sensor (O2S) produces a voltage that varies between 0.1 V and 0.9V under normal operating conditions. The Engine Control Module (ECM) monitors this voltage and determines if the exhaust is lean or rich. If the voltage input at the ECM is about 0.1V the exhaust is lean, and if the voltage input is about 0.9V the exhaust is rich. The ECM constantly monitors the O2S 1 signal during closed loop operation and compensates for a rich or lean condition by decreasing or increasing injector pulse width as necessary.

CONDITIONS FOR SETTING THE DTC
After engine is at normal operating condition, O2S 1 output does not indicate RICH within 7.5 minutes when the following condition are met.
  • Engine speed at 1,500 RPM or more.
  • Vehicle speed at 25-62 MPH.
  • Throttle valve position is open.
  • Engine has been running for at least 140 seconds.

ACTION TAKEN WHEN THE DTC SETS
  • The ECM will illuminate the MIL during the second key cycle in which the DTC sets.
  • The ECM will store the conditions which were present when the DTC set as Freeze Frame Data.

CONDITIONS FOR CLEARING THE MIL/DTC
  • The ECM will turn the MIL OFF on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
  • A DTC will clear after 40 consecutive warm-up cycles have occurred without a fault.
  • A DTC can be cleared by using the scan tool Clear Information function or by disconnecting the ECM battery feed.

DIAGNOSTIC AIDS
Check for the following conditions:
  • Oxygen sensor wiring. The sensor pigtail may be mispositioned and contacting the exhaust system.
  • Poor ECM to engine grounds.
  • Fuel pressure. A condition which causes a lean exhaust can cause DTC P0125 to set. The system will go lean if pressure is too low. The ECM can compensate for some decrease. However, if fuel pressure is too low, a DTC P0125 may be set. Refer to Fuel System Diagnosis.
  • Lean injector(s).
  • Vacuum leaks. Check for disconnected or damaged vacuum hoses and for vacuum leaks at the intake manifold, throttle body, EGR system, and crankcase ventilation system.
  • Exhaust leaks. An exhaust leak may cause outside air to be pulled into the exhaust gas stream past the O2S, causing the DTC P0125 to set. Check for exhaust leaks near the O2S 1 sensor.
  • Fuel contamination. Water, even in small amounts, can be delivered to the fuel injectors. The water can cause a lean exhaust to be indicated. Excessive alcohol in the fuel can also cause this condition. Refer to Alcohol-Contaminants-In-Fuel Test for procedure to check for fuel contamination.

The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.

If any wiring repairs need to be made, Refer to Repair Procedures in Diagrams.

TEST DESCRIPTION
Number(s) below refer to the step number(s) on the Diagnostic Table.
  1. The OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
  2. This step verifies whether the malfunction is a hard failure or an intermittence.
  1. This step verifies whether the ECM is able to receive a signal from the O2S 1.





~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



DRND
New User

Jul 4, 2013, 1:32 PM

Post #14 of 16 (10735 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

I have good experience with this code with toyota 1nz-fe engine i reset code but it take after 15km - 35km
So.....
You should check your system clearly by using car scanner and look at ECT,O2 B1 S1,O2 B2 S2 sensor's values.some time u will feel O2 B1 S1 value is less than other O2 sensor value.but it's OK because O2 sensor locate at after cat(per-cat).but clearly monitor your O2 B1 sensor's value is less than 0.1mv. the ECM monitor this value in time period and set this code
So i swap O2 B1 and O2 B2 sensor then O2 B1 reading was ok.after i drive 100km but not it take this code Wink


Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 4, 2013, 2:48 PM

Post #15 of 16 (10720 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

Sport - this is about THREE years old! Please stick to current threads. Locked for archives and keep spammers out now,

T
_________________________________________
Long retired now


Hammer Time
Ultimate Carjunky / Moderator
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Jul 4, 2013, 3:46 PM

Post #16 of 16 (10711 views)
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  post locked   Re: p0125 (Insufficient Coolant Temperature For Closed Loop Fuel Control) [In reply to]  

I've never heard such an idiotic response either.




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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.





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