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Engine check light codes; Need help figuring out the issue
Topic Started: Oct 20 2017, 06:42 PM (708 Views)
Dantek15
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I have a 1995 3 cylinder geo metro and my engine check light came on a few days ago. I put a fuse into the diagnostics slot and it gave me the codes 31- pressure sensor circuit, 42- crank angle sensor circuit and 51- EGR System & REGT Sensor Circuit. Any idea what could be causing this? Also, I'm not sure if it's related, but I had an issue where I started my car and while driving I couldn't get it passed 35 mph, it seemed to have no power to it. I pulled over to try turning it off and back on, and it wouldn't start back up. After about 20 minutes I was able to start it up again and haven't had the problem again since. Any ideas?
Edited by Dantek15, Oct 20 2017, 10:32 PM.
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freegeo
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You may have gotten some of the codes when the engine was cranking over but wouldn't start. Has the problem happened since then?
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Dantek15
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No the problem hasn't happened again. The codes came up a weekish after it happened
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Moringa
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A number of seemingly unrelated codes all at once may be traced to either a bad PCM ground, or bad 5 volt reference signal. It could also be a PCM on the fritz. The odds that all these things would act up at once are pretty slim.
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Dantek15
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And what could have possibly caused my car to have no real power to it and then not start?
Edited by Dantek15, Oct 21 2017, 01:42 AM.
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Moringa
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Any of the 3 things I mentioned.
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sphenicie


What basic maintenance have you done recently?

Start by cleaning your battery terminals and grounds and make sure they are tight.
Code 51, clean EGR ports and verify EGR system.

Then clear the CEL's and run until the CEL comes on again. Check codes.
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geogonfa
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First good place to start... :type
Tighten/clean the ground wires at the back of the intake manifold and the all the ones under the hood...
Here is some good info on cleaning the grounds...
http://geometroforum.com/topic/5720306/1/
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Woodie
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51 for EGR is pretty much standard, should be cleaned out as a "best practices" sort of thing but that can wait, it won't cause any driveability issues.

MAP sensor and "crank" position sensor are completely unrelated to each other. As has been mentioned, the only thing they have in common is the sensor ground. Please note that the "crank" position sensor is inside the distributor.
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MR1 Kingsbury
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If your exhaust is highly restricted as in a bad Catalytic con. It will run poorly; limiting your speed.
Also the map sensor may get freaked out and set a code when the engine pukes pressure back into the intake side.
take a soft hammer and smack the cat and shake it around a bit. If it rattles with crumbs in it, then it is bad and potentially will clog again.
Is it 5 speed or automatic? A/c or power steering?
Edited by MR1 Kingsbury, Oct 21 2017, 07:31 AM.
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Dantek15
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MR1 Kingsbury
Oct 21 2017, 07:30 AM
If your exhaust is highly restricted as in a bad Catalytic con. It will run poorly; limiting your speed.
Also the map sensor may get freaked out and set a code when the engine pukes pressure back into the intake side.
take a soft hammer and smack the cat and shake it around a bit. If it rattles with crumbs in it, then it is bad and potentially will clog again.
Is it 5 speed or automatic? A/c or power steering?
It's a 5 speed, no a/c or power steering
Edited by Dantek15, Oct 21 2017, 04:43 PM.
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freegeo
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Dantek15
Oct 21 2017, 01:42 AM
And what could have possibly caused my car to have no real power to it and then not start?
A lot of things. Anything related to the fuel system, spark and including electrical issues.
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Moringa
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One other tidbit, about the bad 5 volt reference. You can develop an intermittent short in a sensor or actuator that uses the 5 volt reference voltage. This should throw a code for THAT part, but when the 5 volt reference is shorted and "pulled away" from other parts that use it, then these items may throw a code as well. A good easy to check symptom of this problem is when you turn the key to the run position, before starting. The PCM is dependent on that 5 volt signal, and cannot function without it. So you sometimes have no check engine light come on, when the key is in the run position before starting, when it should be. In that case, the car will not start, until the 5 volt reference is restored. Next time your car won't start, check to see if the CE light comes on, before cranking.
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freegeo
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Moringa
Oct 21 2017, 03:09 PM
One other tidbit, about the bad 5 volt reference. You can develop an intermittent short in a sensor or actuator that uses the 5 volt reference voltage. This should throw a code for THAT part, but when the 5 volt reference is shorted and "pulled away" from other parts that use it, then these items may throw a code as well. A good easy to check symptom of this problem is when you turn the key to the run position, before starting. The PCM is dependent on that 5 volt signal, and cannot function without it. So you sometimes have no check engine light come on, when the key is in the run position before starting, when it should be. In that case, the car will not start, until the 5 volt reference is restored. Next time your car won't start, check to see if the CE light comes on, before cranking.
That's interesting. Does that apply to the metro.

The 5 volt reference supply voltage is important for the input sensors that use it. It can effect the pcm functions it is off more than a volt either way.
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Moringa
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This applies to all vehicles using a PCM. They had to set it up that way, because if it used a 12 volt reference, the PCM wouldn't function if basic battery/charging voltage wasn't normal. I believe the 12 to 5 volt converter is in the PCM itself. So the PCM feeds itself it's reference voltage, unless of course there's something like a short, pulling it away.
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