| Code | Description | Likely Cause | Guardian Mode? | |------|-------------|--------------|----------------| | | Crank Position Sensor | Sensor failure, wiring issue, or gap incorrect | Yes – no start or stall | | 14 | Coolant Temperature Sensor high voltage | Open circuit, bad sensor, or connector corrosion | No – but fuel mixture affected | | 21 | Intake Air Temp Sensor low voltage | Short to ground, bad sensor | No | | 22 | Intake Air Temp Sensor high voltage | Open circuit, bad sensor | No | | 24 | Manifold Absolute Pressure (MAP) sensor | Vacuum leak, wiring, or failed sensor | Yes – reduced power | | 33 | Throttle Position Sensor (TPS) range error | Mismatch between TPS1 and TPS2, or binding throttle | Yes – limp mode | | 34 | TPS circuit low voltage | Short to ground, bad ground | Yes | | 35 | TPS circuit high voltage | Open circuit, reference voltage issue | Yes | | 42 | Knock Sensor circuit | Bad sensor, wiring, or detonation detected | Yes – timing retard | | 44 | Oxygen Sensor (O2) – lean condition | Vacuum leak, fuel pressure low, O2 sensor failed | No | | 45 | Oxygen Sensor (O2) – rich condition | Injector leak, high fuel pressure, MAP/MAF issue | No | | 51 | Fuel Pump circuit | Relay, fuse, wiring, or pump failure | Yes – engine may stall | | 52 | Injector circuit – cylinder 1 | Open or short in injector driver or wiring | Yes – misfire | | 53 | Injector circuit – cylinder 2 | Same as above | Yes | | 54 | Injector circuit – cylinder 3 | Same as above | Yes | | 55 | Injector circuit – cylinder 4 | Same as above | Yes | | 61 | Ignition coil – primary circuit | Coil failure, driver circuit, or wiring | Yes – misfire | | 71 | Engine Overheat (critical) | Water pump impeller, thermostat, blocked intake | Yes – RPM reduction to ~2500 | | 72 | Engine Overheat (warning) | Same as above, lower temp threshold | No – alarm only | | 81 | Low Oil Pressure | Pressure switch, actual low oil, or pump failure | Yes – Guardian active | | 91 | Battery Voltage high (over 16V) | Regulator/rectifier failed | Yes – possible electrical damage | | 92 | Battery Voltage low (under 9V) | Charging system, loose battery cable, dead battery | No – erratic gauge readings | | 101 | Shift interlock fault | Shift actuator, neutral safety switch | Yes – will not start or shift | | 112 | CAN bus communication loss (engine to gauge) | Wiring, terminator, or gauge failure | No – gauges freeze/blank | | 121 | ECM internal fault | Corrosion, voltage spike, or ECM failure | Yes – severe limp mode | | 122 | Guardian Engine Protection active | See root cause code (overheat, oil, knock, etc.) | Yes – RPM limited | | 151 | Fuel pressure sensor out of range | Sensor failed, fuel restriction, or pump issue | Yes | | 201 | Steering angle sensor not calibrated | After service, or sensor disconnected | No – DTS only | | 202 | DTS (Digital Throttle & Shift) calibration lost | Battery disconnected, ECU reset | No – shift issues | Verado-Specific SmartCraft Codes Mercury Verado engines (inline 4, 6-cylinder supercharged) have unique codes:
Mercury Marine’s SmartCraft system is a digital interface that connects your engine, gauges, and vessel systems (like fuel and trim) to provide real-time performance data and diagnostics. When a problem occurs, the system generates a specific SmartCraft Fault Code (often displayed as a 3- or 4-digit number on a SmartCraft gauge or VesselView display). mercury smartcraft fault codes list
