Common Failures - Purpose, Rules and Guidelines

Diagnostics & Repair Intelligence Common Failures
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Purpose

Common Failures is the searchable knowledge base for confirmed, reproducible failure modes. These posts should document verified root causes and fixes so another shop can recognize the pattern, apply the correct repair, and avoid re-diagnosing the same issue from scratch.

What Belongs Here

  • Confirmed failure modes with a verified root cause established by a completed repair.
  • Posts documenting one or more vehicles with the same failure, same confirmed cause, and same fix.
  • Year, make, model, and engine combinations where a known failure pattern applies across a generation or production range.
  • Corrections or refinements to existing Common Failures threads.
  • Follow-up confirmations that add verified cases to an existing thread.

What Does Not Belong Here

  • Active diagnostic cases. Post those in Diagnostics & Repair Intelligence.
  • Third-party warranty or insurance claim handling. Post that in Extended Warranty & Insurance.
  • Customer scripts or advisor language. Post those in Effective Communication.
  • Books, courses, podcasts, training programs, tool buying advice, or scanner reviews. Post those in Resources.
  • General shop discussion that does not document a specific confirmed failure. Post that in General.
  • Off-topic content, personal posts, non-professional content, or venting. These are not permitted.

Required Format

Thread Title

Title format: YEAR MAKE MODEL ENGINE — \[Component\] \[Failure mode\]

Examples:

  • 2017–2020 Honda Civic 1.5T — Oil dilution
  • 2014–2018 GM 5.3L V8 — AFM lifter collapse

Year ranges are encouraged when the failure spans a generation. A single year is correct when the failure is year-specific.

Post Body Template

Every post body must use the following template exactly. Copy, paste, and fill in every field. 

\*\*Vehicle:\*\* YEAR MAKE MODEL ENGINE (include trim and transmission if relevant)
\*\*Mileage range:\*\* the typical mileage range over which this failure presents
\*\*Symptom:\*\* what the customer reports and what the technician observes
\*\*Verified cause:\*\* the actual root cause, confirmed by repair (not theorized)
\*\*Fix:\*\* the repair performed, including parts used and labor approach
\*\*Confirmation count:\*\* how many vehicles you have personally fixed this failure on (state "single confirmed case" if only one)

Attachments and VIN Information

  • Attach photographs, scope captures, or supporting data directly to the post.
  • Do not link to external file-sharing services.
  • Include the last 8 characters of the VIN only if build-specific data is relevant.
  • Do not post the full VIN.

Category-Specific Rules

§5.1 — Parent Category Rules Apply

All rules of the parent category, Diagnostics & Repair Intelligence, apply here. These rules are additional and specific to Common Failures.

§5.2 — Template Required

Every post must use the required body template. Posts missing the template will be edited by moderators to request it. Continued omission after that edit may result in post removal.

§5.3 — Speculation Must Be Labeled

Speculative replies must begin with \*\*Speculation:\*\*.

This includes alternative causes not confirmed by repair, hypothetical contributing factors, or suggestions on a thread that already has a verified cause.

Replies that add confirmed data, another verified fix, a related exception, or a refinement do not require the prefix.

§5.4 — Verified Cause Must Be Confirmed

The Verified cause field must reflect a confirmed root cause from a completed repair. A hunch, guess, or incomplete anecdote is not enough.

§5.5 — Confirmation Count Must Be Accurate

State your confirmation count honestly. Single confirmed case is acceptable. Claiming more confirmed vehicles than you have personally verified is grounds for removal.

§5.6 — Corrections Are Required

If a follow-up case shows the original verified cause was incomplete or wrong, the original poster must edit the post and add a \*\*Correction:\*\* block at the top of the body.

Threads where the original cause is shown to be wrong and the original poster refuses to correct it may be closed.

§5.7 — Confirmed Diagnostic Threads Become New Posts

If a thread in Diagnostics & Repair Intelligence reaches a confirmed common failure, create a new thread here and link back to the original diagnostic thread.

Do not move or convert the diagnostic thread itself.

Enforcement

Edited or Removed by Moderators

  • Title does not follow the required format.
  • Post body is missing the required template.
  • Speculative reply is missing the \*\*Speculation:\*\* prefix.
  • Post is in the wrong category.

Warning and Post Removed

  • Anecdote-only post where the verified cause is only a hunch.
  • Repeated speculation without the required prefix after moderator correction.
  • Refusing to add a \*\*Correction:\*\* block after the original verified cause has been shown to be wrong.

Account Suspended or Banned

  • Knowingly inflating the confirmation count.
  • Posting fabricated repair data.
  • Repeat violations of the parent Diagnostics & Repair Intelligence rules.