check engine light/cracked thermostat??

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  #1  
Old 01-14-04, 07:06 AM
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check engine light/cracked thermostat??

Would a cracked thermostat housing cause a check engine light to come on in a 1997 Isuzu Rodeo?? I found I do in fact have a cracked thermostat, but the mechanic says he's not sure why the check engine light is on. He dind't give me the code either.
 
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  #2  
Old 01-14-04, 10:26 AM
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The question is, has it overheated due to the cracked thermostat housing? Just being cracked will NOT set the check engine light, but if it has run hot because of it then it is possible, but still not definate. If he cant tell you what the code is then you need to go to another mechanic or go to autozone and get them to pull the code for free and post it back here so we can try to help you with the code.
Hope this is helpful to ya,
Billy
 
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Old 01-14-04, 03:10 PM
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The car never overheated due to the crack, just made a mess over the engine at some point. I got the code today, it's P1391...something about a G sensor.

What is a G sensor?
Any relation to the radiotor/thermostat?
And how much can I expect for a G-sensor repair??
 
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Old 01-14-04, 03:42 PM
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Your right, that code is for "G" sensor performance. It's an Izuzu factory specific code meaning it's for Izuzu only. I have no idea what their calling a G sensor. I'm sure it's something we know as a different name in other makes. Someone is going to have to research Alldata or an Izuzu service manual to get an explanation. You can bet it's the reason you light is on. Not necessarily the sensor's fault but the readings it's seeing.
 
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Old 01-14-04, 03:49 PM
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That code refers to a wheels speed sensor circuit performance issue. Unless you have a diesel engine then it refers to a Glow plug circuit low input. So that code actually doesnt have anything to do with your engine unless of course if you have the aforementioned diesel engine.
Hope this is helpful to ya,
Billy
 
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Old 01-14-04, 06:19 PM
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You might want to look again Billy. P1391 is a G sensor issue. The poster is right.


P1390
G Sensor Circuit Intermittent Voltage Low

P1391
G Sensor Performance

P1392
G Sensor Voltage Low

P1393
G Sensor Voltage High

P1394
G Sensor Intermittent Voltage High
 
  #7  
Old 01-15-04, 03:43 AM
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This is exactly what this OBDII code means:

P1391 Glow Plug Circuit Low Input (Bank 1)

P1391 Wheel Speed Sensor 1 - G - Sensor Circuit Performance

P1391 Wheel Speed Sensor 1 - G - Sensor Circuit Performance
Billy
 
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Old 01-15-04, 04:41 AM
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Looks like it has a dual meaning depending on the manufacturer. Under Izuzu specific OBDII it only shows the "G sensor" portion of that on the chart I'm looking at. Does G sensor definately refer to glow plug? Sure sounds like their describing O/2 voltage parameters with the high/low and performance issues.
 
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Old 01-15-04, 04:44 AM
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Im gonna look at Alldata at the shop today and see what it says there. I will post back around luncktime.... hopefully.
Billy
 
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Old 01-15-04, 07:51 AM
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I appreciate all the help guys. Do either of you happen to know what exactly a G-sensor is? I'm assuming some type of emission sensor, but am not sure.

I had the code cleared after having the thermostat replaced and all antifreeze washed off the car. So far it hasn't popped back on. *knocks on wood* I can only hope that the problem is fixed.
 

Last edited by HotBacon; 01-15-04 at 11:24 AM.
  #11  
Old 01-15-04, 11:09 AM
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As I said before the "G" sensor will have absolutely nothing to do with the coolant or the thermostat housing. That code in fact refers to a "G"ravity sensor. Which explains why the OBDII code specifies wheel speed. I left the printout at work when I cant home for lunch as I was (am) really busy today and am just now (almost 2pm) getting home for my lunch. I will post what is says this evening.
Billy
 
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Old 01-15-04, 11:24 AM
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"G" sensor...

the G sensor is an accelerometer mounted in the rear of your center console and senses deceleration during 4WD operation. This allows the ABS system to compensate for changing road conditions. (I won't pretend to understand the theory behind this but it is straight out of the service literature). I can tell you that it shares 5 volt reference with the MAP sensor (this is an engine sensor) and so that may be how/why an ABS sensor turned on the MIL (check engine lamp). The other thing that may be at work here is that some aftermarket scan tools don't interpret information properly on OBDII equipped vehicles. This is where the manufacturer's dedicated scanner (Tech 1) may have an advantage.

Have you had any problems with the ABS light coming on? If so, perhaps a failing G sensor may be affecting the MAP sensor circuit and causing the MIL to come on...but the scanner that was used couldn't differentiate properly...just a theory. Asian electronics do some strange things...this i DO know!

None of this relates to the coolant leak...unless coolant sprayed all over the MAP sensor and caused some weird voltages on that shared circuit.

I'd keep an eye on it...if it doesn't come back on after a couple weeks...I wouldn't stress about it.

I'd keep an eye on it
 
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Old 01-15-04, 11:40 AM
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This situation gets deeper and deeper! I haven't had the ABS light come on, and the check engine light came on both times upon startup (no wheel speed, no brake involvement). Due to the fact that the light came on at startup led me to believe that Advance Auto Parts was on the right track when they said something about the code standing for an ignition problem.
 
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Old 01-15-04, 03:16 PM
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You just had a master technician give you a detailed, technical explanation of exactly what that code and sensor is and now you think the part time parts clerk at Auto Zone knows more! DUH! The light came on at start up because the ECM did s system check and saw a problem with the circuit.
This is what frustrates the hell out of a busy technician trying to help you.
 
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Old 01-15-04, 03:34 PM
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LOL..... Thats really funny. You have 2 ASE Master Techs and me trying to help you with whats going on with your vehicle and you wanta believe the zit faced kid at the Advance Auto because he has a fancy little code reader gadget. This job gets more fun every day. I wish my real job... being a professional automotive technician.... was this much fun.
Billy
 
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Old 01-15-04, 03:39 PM
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what an ass

There's something we have in the English language that is called past tense. This can be seen in my sentence "...the light came on at startup LED me to believe that Advance...". Not once in my previous post did I say I didn't believe carguyinva, or did I ever say I think its the ignition. I was simply supplying additional info, thinking that maybe w/ what was already posted someone might be able to tell me what's going on. Do us all a favor and if you don't have anything to add of substance, don't post.
 
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Old 01-15-04, 03:51 PM
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HotBacon.... You need to go back and read ALL of the replies that have been posted here. EVERY ONE was posted to attempt to help you. Then you go and discredit all of the help that is being offered by saying that the kid at Advance Auto was right and we are wrong. If you want to trust that and dont want our help please dont ask anymore. Im sure all of the experienced people here are more than willing to help people who are interested in using the advice given to solve their problems. I dont know about Carguy or Desi, but im sure I speak for every technician who has contact with customers, that the.... Thats what the guy at Advance or Auto Zone said it was..... You know what happens then? We try to explain that a proper diagnosis is needed and that what the kid said may or may not fix your car and you say well thats what he said and thats what I want done.... So then you think.... This guy is just trying to get me for diagnostic time that I dont need.... Then the whole mechanics are just trying to gouge me for more money bit starts over.
So before you discredit the experience here think about it and let it sink in. And remember when you make comments like that I can make them go away so DONT DO IT!!!
Billy
 
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Old 01-15-04, 03:54 PM
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Originally posted by HotBacon
Due to the fact that the light came on at startup led me to believe that Advance Auto Parts was on the right track when they said something about the code standing for an ignition problem.
Originally posted by HotBacon
Do us all a favor and if you don't have anything to add of substance, don't post.
OK, I'm done with this thread. This guy's on his own.
 
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Old 01-15-04, 03:58 PM
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Another one that can't read, or one that reads the first sentence only?

I'll refer you to my last post entitled "what an ass" when I reiterated that I did NOT choose to believe the "zit faced" Advance guy over a master tech. Rather, I was simply trying to supply more information to try and see if that would jive with any of your opinions.

As I'm sure that the two of you will now refuse to help me anymore, I'd like to thank you for what info you did give me.
 
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Old 01-15-04, 04:14 PM
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Im not going to refuse to help you, but I think CarGuy pretty much summed up what I was going to post this evening, so in essence he beat me to the punch. I suggest you take his advice and if the light comes back on feel free to post another query.
Until then this post is closed.
Billy
 
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