2001 Protege coil pack resistance
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Joined: Feb 2026
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2001 Protege coil pack resistance
ES 2.0. 160k miles.
Problem started with code P303 and rough running engine at idle and under acceleration, this is an intermittent issue.
Things I have tried:
1. Replaced coil pack for cylinders 2&3 with a used coil pack (have ordered two new coils and wires, waiting for delivery)
2, Replaced cyl.3 sparkplug (all plugs were replaced 1,000 miles ago)
3.Removed coil electrical connectors and blew out with air, seem to be in good condition.
4. Cleared the engine code
Now the engine is running better and the code has not come back. But there still seems to be an engine miss present. This is a new to us car so do not know if the timing belt has been replaced or not but would think if timing had slipped then the engine would run poorly all of the time.
Questions: 1. Reading appr 1500 ohms between pins 1&2 / infinite ohm between pins 1&3 and pins 3&2. Is this normal??
2, I will be replacing the coil packs and wires once the new parts arrive. Any other suggestions??
Problem started with code P303 and rough running engine at idle and under acceleration, this is an intermittent issue.
Things I have tried:
1. Replaced coil pack for cylinders 2&3 with a used coil pack (have ordered two new coils and wires, waiting for delivery)
2, Replaced cyl.3 sparkplug (all plugs were replaced 1,000 miles ago)
3.Removed coil electrical connectors and blew out with air, seem to be in good condition.
4. Cleared the engine code
Now the engine is running better and the code has not come back. But there still seems to be an engine miss present. This is a new to us car so do not know if the timing belt has been replaced or not but would think if timing had slipped then the engine would run poorly all of the time.
Questions: 1. Reading appr 1500 ohms between pins 1&2 / infinite ohm between pins 1&3 and pins 3&2. Is this normal??
2, I will be replacing the coil packs and wires once the new parts arrive. Any other suggestions??
Senior Member
Joined: Oct 2018
Posts: 10,334
Likes: 198
From: Northern California
You already started another thread asking the same question and was responded to by at least myself?
2001 - Mazda Forum - Mazda Enthusiast Forums
2001 - Mazda Forum - Mazda Enthusiast Forums
DTC are starting point to begin looking into the possible cause not the absolute cause of issues and the check engine light . Replacing random parts does not always correct the issue and often distracts from finding the actual cause because DIY fixate on the single cause and not all the possibilities.
When you cleared the DTC all you did was turn off the check engine light.
If the issue was not correct 2 things, you would have found the DTC and maybe other DTC in the permanent file area of the ECU and after 1 to several engine cycles the check engine light WILL be reactivated.
So my suggestion is to either scan directly connecting to the OBDII diagnostic connector with a better-quality scanning device and at least look in the 3 main areas to start looking for the root cause of your problems.
Cant teach diagnostic skills on a single post (it actually takes min several weeks of learning the book work study and then applying in the real world hands on training)...... it just not that easy or there would be more general automotive mechanics actually knowing OBDII diagnostic trouble shooting.
At best at least wait until you have all 4 of your coils and wires boots and springs if applicable ( I did not look up your exact model Mazda) and then start over if the problem persists.
1000 miles and spark plug with your miles is also a possible spark plug issue that should not be overlooked.
When you cleared the DTC all you did was turn off the check engine light.
If the issue was not correct 2 things, you would have found the DTC and maybe other DTC in the permanent file area of the ECU and after 1 to several engine cycles the check engine light WILL be reactivated.
So my suggestion is to either scan directly connecting to the OBDII diagnostic connector with a better-quality scanning device and at least look in the 3 main areas to start looking for the root cause of your problems.
Cant teach diagnostic skills on a single post (it actually takes min several weeks of learning the book work study and then applying in the real world hands on training)...... it just not that easy or there would be more general automotive mechanics actually knowing OBDII diagnostic trouble shooting.
At best at least wait until you have all 4 of your coils and wires boots and springs if applicable ( I did not look up your exact model Mazda) and then start over if the problem persists.
1000 miles and spark plug with your miles is also a possible spark plug issue that should not be overlooked.
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