2007 Chevrolet Cobalt Help

Tiny
BABYCODY3
  • MEMBER
  • 2007 CHEVROLET COBALT
  • 2.2L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 134,000 MILES
Got this car it run fine no issues no lights came on I hooked up a machine to tell me it was anything wrong nothing had it almost 2 weeks and it just dies in the parking lot It blew the intake fuse run great for 3 weeks then a check engine light came on my coolant thermostat was reading ----f Took it to the dealership they hook your machine up to it it's telling me that the radiator sensor needs to be replaced. A few days ago I was driving and it just died thankfully I was able to coast into an empty parking lot. Check the fuse that blow the last time and it wasn't blown it would not start! Could it be that my car was reading really low then really high then really low the car shut itself off for safety reasons should I start with the radiator sensor. If that doesn't fix the problem then should I try the thermostat! I'm on a fixed income
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Tuesday, December 2nd, 2014 AT 6:45 PM

6 Replies

Tiny
CARADIODOC
  • EXPERT
You'll save money by getting a proper diagnosis. First you have to understand that diagnostic fault codes never say to replace parts or that they're bad. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. When a sensor is referenced in a fault code, it is actually what is is causing it to set about half of the time, but even less so with a temperature sensor. Most of them only have one part inside, a temperature-dependent resistor, (thermistor), and those have an extremely low failure rate. You're much more likely to have a wiring problem related to that sensor, especially due to the way it's acting.

A temperature sensor will not cause an engine to stall. There might be a different fault code related to that, otherwise your mechanic can connect a scanner to view live data during a test drive. If it has a record feature, he can record the event when the problem occurs, then he can replay it slowly later to see what changed that might be a clue to the cause.
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Tuesday, December 2nd, 2014 AT 7:02 PM
Tiny
BABYCODY3
  • MEMBER
The check eng light is on and it saying radiator sensor needs replacing The only reason I asked about the thermostat is because I saw another question about the same issue I am having in a mechanic said to try replacing the thermostat so I was just trying to see if that's what it was thank you for your help
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Tuesday, December 2nd, 2014 AT 7:07 PM
Tiny
CARADIODOC
  • EXPERT
I can guarantee the fault code did not say to replace a sensor. That is a real common misinterpretation and the number one reason people end up with a boxful of parts they "tried". Replacing random parts is the least effective and most expensive way to diagnose a problem, and it introduces a whole bunch of new variables the Engine Computer has to learn and adjust for. I don't want to see you waste your money on parts unless you already have them laying around.

I need to know the exact fault code number to have an idea of how to proceed. You can also go here:

http://www.2carpros.com/trouble_codes/obd2/P0100

to look up the code descriptions. You'll see none of them use the word "defective" or anything else that says to replace something. If you still aren't convinced, find a used sensor in a salvage yard. In the unlikely event it solves that problem, you'll still save money, and if it doesn't, you'll have saved even more.

Sorry that I overlooked the blowing fuse problem. I do have a trick for that too but it will be more effective when the problem occurs more often.
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Tuesday, December 2nd, 2014 AT 7:34 PM
Tiny
BABYCODY3
  • MEMBER
Don't no the code and can't move car Iwill have to wait for a friend to get back in town that has a code thingy and when the other person did it he looked up the code and it was the sensor was reading low bats what the person told me and that what I was going by
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Tuesday, December 2nd, 2014 AT 7:44 PM
Tiny
CARADIODOC
  • EXPERT
Dandy. An open circuit, meaning a break in a wire to the sensor, will set a code for "high voltage". That's pretty common. It's less common to get one for "low voltage", but that one for sure can't be caused by the sensor. There are two wires going to a temperature sensor. One is its ground wire which will typically have 0.2 volts on it all the time. The other one is the signal wire that is fed with 5.0 volts from the computer. When the circuit is working properly, the sensor draws that voltage down to between 0.5 and 4.5 volts. That is the acceptable range for most 5.0 volt sensors. It's the voltage going outside that range that sets a fault code.

For a "voltage too low" code, it is almost always due to the signal wire being grounded. That will draw its voltage down to 0.0 volts which is outside the acceptable range. When that occurs right after some other service, it's usually due to pinching a wire accidentally. When it occurs on its own, the most common cause is a wiring harness has been sliding back and forth as the engine rocks, and the insulation has rubbed through, or it is draped over a metal bracket with sharp edges that cut into the wires.

You may be able to find this one on your own with just a digital voltmeter, but the readings will only be valid if the sensor remains plugged in. You can back-probe through the rubber seals where the wires go through into the connector. Find the wire with approximately 2.0 to 4.0 volts. The voltage will be lower as the temperature is higher. While watching the meter, tug and wiggle on the wiring harnesses. If you see the reading suddenly change, you're in the area that's causing the problem
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Tuesday, December 2nd, 2014 AT 8:03 PM
Tiny
BABYCODY3
  • MEMBER
Thanks
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Tuesday, December 2nd, 2014 AT 8:16 PM

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