p1400 & p0125 (will they cause problems?)

[oplix]

I'm pulling codes p1400 and p0125 which are the manifold pressure and coolant temperature sensors.

I don't really have any problems driving the car even with these codes. Will the ECU try to put the car into safe mode if these are active?

 

[bboyalan]

Hi. I doubt that the two codes will toss your car into a limp mode, but rather, the fact that those sensors are on their way out will affect the information your ECU receives to make calculations. Are you clearing them on the constant? They're pretty easy as hell to replace bro . The MAP sensor tends to be pricey brand new, so it's your call on that one.

Also, based upon your observations, have you noticed if it takes longer than usual for your car's temp gauge to show fully warmed-up? IIRC, with a bad sensor, the ECU will compensate for a low temperature by adding more fuel causing you to run rich [just like from a cold start]. I read about this in my dad's books from his automotive schooling and also saw it first-hand on the DSM.

 

[spyderturbo007]

The coolant temp sensor code will basically dump you in limp mode. When they die, they report a coolant temp of -40 degrees to the ECU. This causes the ECU to think the car is cold when in fact it has warmed up to operating temperature. Basically, the ECU will never enter closed loop and will be running pig rich all the time.

Do you have a logger you can use to check the coolant temp? If not, I would just throw on a new sensor, since mine was only $26 from the dealer.

Just remember to tell them you need the sensor for the ECU and not the sensor for the gauge.

 

[oplix]

my logger reports anywhere from 210-250 degrees for the coolant.

 

[spyderturbo007]

That's odd, although anything above 216 or so and that can be a problem. 250 degrees and you should be in the red on the dash gauge.

I'm going to have to look into this a little more, because according to the ECU you aren't entering closed loop, but according to the coolant temp sensor, you should be. Give me a little time and I'll see if I can dig something up for you.

 

[spyderturbo007]

Actually, now that I think about things, it could also be your front O2. I've never encountered the problem myself when dealing with a dead front O2, but I remember someone saying that caused them to get the P0125 CEL.

Can you take a look at your front O2 after clearing the codes during idle and light cruise and see if it's oscillating like it should. Just make sure the car is warmed up properly.

 

[oplix]

are you talking about the o2 voltage? Theres nothing wrong with my front o2. If there was, the car would run like crap. I do get voltage reading for the front o2 last time I checked in my logger. I just got the logger less than a week ago though so I haven't fiddled with it much.

 

[spyderturbo007]

are you talking about the o2 voltage? Theres nothing wrong with my front o2. If there was, the car would run like crap.

Actually if the front O2 was bad, you wouldn't notice anything except for the Fuel Trim Malfunction (Bank 1) CEL. You'll be running a little rich at idle, but it doesn't cause driveability problems.

 

[mandrigues]

Ok I have had the exact same problem! so on my car it is always in closed loop always trying to warm up the car! so its running 11.4-10.9 on the AFR gauge, so I stoped driveing it. and I have tryed to mess with the coolant temp sensor, but my major problem is the, car is a 97, ecu is a 95 eprom, engine is 92 6 bolt forged, when I try to mess with the pigtail on the harness it does not fit a 92 coolant temp sensor so I messed with the prongs till it fitted, but it still did the same thing the car runs fine takes 5-10 mins to get warmed up to middle temp on the gauge that seems a lill long? so I think the ECU is compinsating for one of the sensors since it is takeing so long, but since I have read that the front o2 sensor on the o2 housing would cause this I will go home and see if that is the problem really hope it is I just bought AEM plug in play and a 60trim precision turbo 590hp I think man I hope that is the problem!

 

[mandrigues]

Solved my problem, the reason check engine light was on was becuse could not distinguish between open and closed loop, when I did my engine swap I had a 1g engine in a 2g car so the sensor was not the right year so it didnt understand. I changed the coolant temp sensor for that then reset ECU bammm it was good . then for the rich running yes same thing 1g o2 sensor caused me to run 10.9 all the time ughhh that was bad. now that I have the right year sensor it runs 14.7 idle and 10.0 with full boost