How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Amedee Your Own Question
Amedee, Saturn Technician
Category: Saturn
Satisfied Customers: 26459
Experience:  ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
Type Your Saturn Question Here...
Amedee is online now
A new question is answered every 9 seconds

Saturn ion: Hey..It was misfiring and check engine light..ICM

Customer Question

Hey, I have an 03 saturn ion. It was misfiring and check engine light started blinking. I took it to a mechanic and he said the ICM was bad. I took it home and replaced it with an aftermarket part. I also replaced all the spark plugs because one was very fouled. It has been about a week and is giving me the same problems I had before. Could it be a faulty part or is the coil pack bad as well? It is all very easy to do so any advice or way to test the ICM or coil pack would be great.
Submitted: 7 years ago.
Category: Saturn
Expert:  Amedee replied 7 years ago.



Do you know the code number in the computer?

Customer: replied 7 years ago.
I think it was p0 something. I cant remember, I just tried starting it and it almost choked out just like before. No power to it. I might be able to get a reader on it later today
Expert:  Amedee replied 7 years ago.
That would be great! Just let me know!
Expert:  Rick replied 7 years ago.
Hi I can answer your question. please simply make a deposit and then accept the answer and we can help you. Do you have a p0420 in you system?
Customer: replied 7 years ago.
That was the old code I think before I replaced the ICM. I just scanned it and it gave me P0520 and it told me Enging oil pressure sensor/switch. When I start it the vehicle shakes and smells like oil/gas. I looked up the part online and its a cheap easy fix. Do you think that this is related to my previous problem or just a coincidence it happened a week after I replaced the ICM. Do I need to replace the coil pack? The Scantool showed no misfires. Its an Innova tool. Any help/info would be great thanks
Expert:  Amedee replied 7 years ago.

Hello there!


When was the last time the engine was tuned up? No, not just plugs, but a full tune up! The whole nine yards! Any part of the secondary ignition will do this including the ignition coil or coils! This sounds like a classic ignition misfire! They usually go bad under a load like under acceleration, but can be noticeable at any time. It is very important to have your engine equipped with good tune up parts or you may be causing damage to other components of you car like the catalytic converter which can be expensive!


Possible causes:

Ignition misfire causes by any bad tune up part and or ignition coil or coils.
Bad spark plugs, spark plug wires and cap and rotor (if equipped)
Wrong tune up parts spark plug, wires etc...

Insulator cracks.
Improper gap.
Burned electrodes.
Heavy deposits.


The quickest way to check the ignition components, is by looking closely for leaking secondary voltage. Visual look at all the tune up parts to see if you can see any sparks coming from any of the wires or coil (or coils) when the vehicle is running. If not, you can put your hand on the coil/coils and wires when the engine is running and see if you feel any small voltage leaking form the tune up parts. Check spark plug wires by connecting ohmmeter to ends of each wire in question. If meter reads over 30,000 ohms, replace wire(s).
ALso, with engine running, spray coils and plug wires with fine water mist to check for shorts. It will leak secondary ignition voltage from the tune up parts caused by high resistance from carbon tracking if they are bad. This is very common if the tune up parts are not changed regularly!

If any is found, the tune up parts are simple bad an will need to be replaced! If none is found than you can spray a mist of water on the tune up parts when the engine is running and see if that causes the engine to stumble or run rough at all. Again, if it does, the tune up parts are bad and will need to be replaced!


Here is some info about your code.




1. Using a Digital Volt Ohm Meter (DVOM), check the voltage on circuit 231 Tan/Black wire at the oil pressure switch with the switch plugged in and the engine running. The voltage should be near 12 volts.

2. If the voltage is low, unplug the connector at the oil pressure switch and again check the voltage on the Tan/Black wire.

3. If the voltage is still low, check the Tan/Black wire from the oil pressure switch to the Engine Control Module (ECM) connector C2 pin 37 for a short to ground.

4. If the voltage jumps up to near 12 volts with the oil pressure switch unplugged, check the oil pressure. The oil pressure switch should open at about 4.5 PSI.


Potential Causes:


Insufficient Oil Pressure
Oil Pressure Switch



Tips: Conditions for Setting the DTC P0520 The ECM detects that the Engine Oil Pressure (EOP) sensor signal circuit is pulled low. The above condition is present for greater than 5 seconds. When the oil pressure is above 4.5 PSI, the oil pressure switch opens, and the ECM senses a high signal voltage. The ECM monitors the oil pressure switch signal circuit and sends a class 2 message to the Instrument Panel Cluster (IPC) indicating the switch status. When the engine oil pressure is low, the engine oil pressure switch closes, the signal circuit is low, and DTC P0520 sets.

P0520 Engine Oil Pressure Switch Circuit Malfunction

Possible Causes
EOP switch connector is damaged (check pins for damage, and moisture)
EOP switch signal circuit is shorted to ground
EOP switch has failed
ECM has failed

Customer: replied 7 years ago.
The engine has a coil pack no exposed terminals. It also has boots attached to it. All in great shape, new spark plugs at 100,000 miles as recommended by saturn. When misfire started happening I replaced spark plugs and faulty ICM. Still has original coil pack and boots but there is no cracking and look like they are in great shape. I will replace the oil pressure sensor tomorrow. Hopefully that will do it since the wire seems to be fine
Expert:  Amedee replied 7 years ago.

Are there any other codes in the computer?


DO you have access to a scanner that can read live data?

Customer: replied 7 years ago.
Yes I do its a innova 3130. No other codes were listed
Expert:  Amedee replied 7 years ago.

SO can you read live data? I am not familiar with this scanner.


Can you read history and current misfires?

Customer: replied 7 years ago.
It reads anything in the history that hasnt been cleared no misfires showed when i started the car but then it started smelling and runny very badly so I shut it off. Started again just now and ran okay but very cold out still bad smell. Cleared the code and it came right back. Live read worked everything looked okay
Expert:  Amedee replied 7 years ago.
DOes it run rough all the time or just at idle or under a load?
Customer: replied 7 years ago.
I was afraid to drive it after it shook so bad before and smelled bad. Has been driving fine the last week since I replaced the ICM and spark plugs. Before I did the I was getting the random misfire code and it would shake and have no power at high speed occaisionaly. I looked it up it was P0300 random misfire. But since i just started it and it was 33 degrees out it seemed to run okay just the same code(oil sensor) even after clearing it.
Expert:  Amedee replied 7 years ago.

SO it still runs rough but no code p0300?


Let me know how things go after you replace the sensor. I don't think this will help your run problem but might help out for your code.

Amedee, Saturn Technician
Category: Saturn
Satisfied Customers: 26459
Experience: ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
Amedee and 3 other Saturn Specialists are ready to help you
Customer: replied 7 years ago.
Extremely rough at idle on occaision. That sensor if faulty could help the rough idle right? I will replace it tomorrow and definatly let you know if still have problem. No p0300 code at all since replaced ICM
Expert:  Amedee replied 7 years ago.

I don't think that the oil pressure sensor will cause your rough running.


But if you want to get rid of the code anyway, replace it and let me know how it goes. I will be on line all day tomorrow.

Customer: replied 7 years ago.
Hey again, didnt replace the oil sensor. Cleared the code and hasnt came back. Car is running fine again. Very cold out though. No light, drove around for around 20 min, MIL came on again. Got home check it and it said P0420 Catalyst System below threshold (Bank 1) I have the freeze frame data if you need it but it is just basic info that all looks normal. Thanks for you time again
Expert:  Amedee replied 7 years ago.
SO would you like to go after this p0420 code?
Customer: replied 7 years ago.
Yea if you think it would help me with the rough idling problem. Car is running fine today though, just popped that code. I dont mind paying for your help
Expert:  Amedee replied 7 years ago.
Well, that code is a converter code. That would not have anything do do with the engine idling rough. If anything, it would be plugged causing a low power problem but that is not what is wrong here. We have a rough or unstable idle.