Engine diagnostic plug identification

D

DavidO

Member
Joined
Oct 15, 2025
Messages
16
Wanting to confirm that this is the plug for checking engine codes. There is another plug next to this one, triangle shape. YANMAR 4BY-180. R-27 2011. Thanks.
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I have owned a 2012 R27 since April 2017. In case you didn’t know, your Yanmar 4BY2-180 is mostly a BMW 1.995L 4-cylinder turbo diesel that has been marinized by Yanmar. Several years back, I had my engine serviced by Yanmar dealer. They could find no way to read any codes. As far as I am aware, the Yanmar engine display at your helm is the only way to read codes. The few times a code was shown on the Yanmar engine display, it was so nebulous and non-specific that it was zero help in diagnosing the problem.

If you happen to discover a way to use those ports, please reply to this thread for other 4BY2 owners.
 
Interesting. I do have the code reading at the helm. I have a bad glow plug and will replace when the parts arrive next week. My concern is, will the code clear on its own or is a code reader needed.
 
DavidO said:
Interesting. I do have the code reading at the helm. I have a bad glow plug and will replace when the parts arrive next week. My concern is, will the code clear on its own or is a code reader needed.
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Interesting. What code was/is displayed that led you to the glow plug diagnosis? My guess is that the code will no longer display once the condition causing it is resolved.
 
CaspersCruiser said:
Interesting. What code was/is displayed that led you to the glow plug diagnosis? My guess is that the code will no longer display once the condition causing it is resolved.
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Code: P0673 Glow plug #3. Corresponds to list of codes in Yanmar maintenance manual.
 
On the helm display, hold the far right button for 5 seconds, then a menu will appear to allow you to view codes.
 
It’s been 5+ years and I can’t remember the exact details, but the code generated when my engine quit due to a failed fuel pump was no help in diagnosing the problem. Obviously, your code was a bullseye!
 
CaspersCruiser said:
It’s been 5+ years and I can’t remember the exact details, but the code generated when my engine quit due to a failed fuel pump was no help in diagnosing the problem. Obviously, your code was a bullseye!
Click to expand...
Replace all four glow plugs, code fault at helm went away.
 
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