
Spark Plug Reader
Read it, don't replace it
0 ratings
Free
In-App Purchases
Rating summary
About
Plug Read turns a spark plug into a diagnosis, and now it torques the replacement in correctly too.
MATCHED BY EYE, NOT BY PART NUMBER
Eight appearances, drawn as they come out of an engine. Tap the match and you get what it means and what to check, in the order worth checking it.
INSTALL TORQUE, BY THREAD AND SEAT
Pick the thread size and seat type, the head material, and get the torque range in both ft-lb and Nm, plus the hand-tight-and-turn fallback for when you do not have a torque wrench. Cross a plug wrong and you either strip the threads or leave it loose enough to blow out under compression, and the difference between right and wrong can be as little as five foot-pounds.
THE PLUG IS THE CHEAPEST WINDOW INTO AN ENGINE
Five minutes with a plug spanner tells you more about mixture, timing and oil control than an hour of guessing.
NO PART NUMBERS, NO DATABASE
Nothing here goes out of date, because it works from the plug in your hand and the thread you are installing into rather than a list of engine models.
WORKS OFFLINE
No account, no signal.
The torque table is a published general reference cross-checked across several independent sources, not a measured specification for any specific engine. Manufacturer torque specification always takes precedence.
Show more
What's New in Spark Plug Reader
1.0.1
September 18, 2026
Refreshed screenshots and minor presentation improvements. No changes to how the app works.
1
Subscriptions & In-App Purchases
$4.99
Full Version
All eight readings and heat range.







