Mercury Smartcraft Fault Codes List 99%

| Code | Danger Level | Action | | :--- | :--- | :--- | | | CRITICAL | Shut down immediately. Running for 30 seconds can warp heads. | | 111 (Water in Fuel) | HIGH | Change fuel filter before next start. Do not run hard. | | 12 or 13 (Crank/Cam Sync) | CRITICAL | Engine will not start. Do not crank continuously. | | 544-1 (No Sea Water Pressure) | CRITICAL | Impeller is destroyed. Shut down. | | 1078 (High Voltage >16V) | CRITICAL | Disconnect battery. ECM damage imminent. |

| 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 | mercury smartcraft fault codes list

You don't always need Mercury's CDS G3 diagnostic software. Many SmartCraft systems allow code retrieval via the gauge: | Code | Danger Level | Action |