Mercury V8 300

H ..........
HORN_OutputFault
Fault Type: Horn: Guardian: UFC: Transmission to Helm: Freeze Frame Priority:
Nonsticky None 100% 3152‑16 Yes 2
Explanation
The warning horn does not appear to be working properly; the PCM detected a problem when trying to send a signal to the
horn.
Possible Causes
• Wiring problem
• Failed horn
Summary of Fault Correction Possibilities
• Inspect the wiring to the helm.
• Replace the horn.
I ..........
IAT_RangeHigh
Fault Type:
Horn: Guardian: UFC: Transmission to Helm: Freeze Frame Priority:
Nonsticky Caution 100% 511‑24 Yes 2
Explanation
The intake air temperature (IAT) sensor does not appear to be working properly; the PCM received a signal that is above the
valid limit.
Possible Causes
• Wiring problem
• Defective sensor
Summary of Fault Correction Possibilities
• Correct the sensor wiring problem.
• Replace the sensor.
IAT_RangeLow
Fault Type:
Horn: Guardian: UFC: Transmission to Helm: Freeze Frame Priority:
Nonsticky Caution 100% 511‑25 Yes 2
Explanation
The intake air temperature (IAT) sensor does not appear to be working properly; the PCM received a signal that is below the
valid limit.
Possible Causes
• Wiring problem
• Defective sensor
Summary of Fault Correction Possibilities
• Correct the sensor wiring problem.
• Replace the sensor.
Fault Codes
90-8M0146617 eng JULY 2018 © 2018 Mercury Marine Page 4A-23