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Can coils be bad even though they look okay?

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6 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

Discussion summary

YOUR RESEARCHCan coils be bad even though they look okay?

Leading reported evidence

Check ignition coils

Performed · outcome unconfirmed

No successful repair reported for this finding.

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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.

Discussions that performed work without a confirmed outcome
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Performed · outcome unconfirmed · Original poster

I visually checked the coils on both banks and they look okay at glance.

Original post Read captured discussion
Can coils be bad even though they look okay?

Suggestion

Check the coil packs:

Original post Read captured discussion
Can coils be bad even though they look okay?
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Leading evidence: 'Check ignition coils' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check ignition coils' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.

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1 matching discussions · 6 captured posts examined · 0 partial discussions

Compare 1 other evidence results

Check spark plug connectors

Suggestion or failed attempt

No successful repair reported for this finding.

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Reported fixes
0
Unsuccessful attempts
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Discussions
Read evidence and context

Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.

Discussions that contain suggestions
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion

Check the spark plug connectors:

Original post Read captured discussion
Can coils be bad even though they look okay?
Frequently discussed actions (2)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Check ignition coils

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that performed work without a confirmed outcome
1
Discussions that contain suggestions
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Performed · outcome unconfirmed · Original poster

I visually checked the coils on both banks and they look okay at glance.

Original post Read captured discussion
Can coils be bad even though they look okay?

Suggestion

Check the coil packs:

Original post Read captured discussion
Can coils be bad even though they look okay?

Check spark plug connectors

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion

Check the spark plug connectors:

Original post Read captured discussion
Can coils be bad even though they look okay?
Coverage and how to read this overview

Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.

6 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

  • Rennlist: 1 discussions

0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.

0 acknowledgements have no verified action link; they do not establish a repair result.

Generation: 20261026T200546Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

Was on the track during a DE today and the check engine light came on for a few seconds. It turned back off but when I finished I pulled the codes and found that I had a misfire on cylinders 4 and 5. I visually checked the coils on both banks and they look okay at glance. No cracks or other imperfections, in fact they actually look pretty new. But on the passenger side of the engine there is some oil weeping towards the front of the car. Not enough to leave anything on my garage floor but it's not absolutely dry like the driver's side is. So do these codes mean I should still consider changing out my coils or can it be something else?

POST 2Original post

Sure...could be coils...but a misfire could be several things. No, you can't tell they're bad by looking at them. Just so I'm clear..the oil weeping is on the same side that had the misfire right?

POST 3 / ORIGINAL POSTEROriginal post

Quotes source post: 8860769

The misfire happened on both sides. Because I assume cylinders 4 and 5 are on opposite banks, correct?

POST 4Original post

Coils or the spark plug connectors can go bad. Check the spark plug connectors: They should be about 2K ohms. Check the coil packs: Main terminal to a good ground 0.3 to 0.7 ohms (max) at about 68 degrees F

POST 5Original post

1,2,3 cylinders on drivers side 4,5,6 on passenger side 1 and 4 cylinders are most rearward cylinder. Numbering differs from how I used to work on US cars long ago.

POST 6 / ORIGINAL POSTEROriginal post

Quotes source posts: 8860834, 8861001

Thanks Loren! I'll test those this evening and see if they are providing me with acceptable readings. In that case the error codes would have come from the bank that does have the weeping oil. Driving to the office this morning the car behaved as it normally would but I want to get this fixed before it comes back with even worse symptoms.

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