B1115 – Electric water pump malfunction (Mitsubishi)

Mitsubishi-specific code — factory diagnostic data

Last updated: March 30, 2026

Definition source: Mitsubishi factory description · Autel MaxiSys Ultra & EV. Diagnostic guidance is based on factory-defined fault logic for this code.

B1115 means the Outlander has a problem with an electric water pump, and the vehicle may not control temperatures correctly. You might notice poor cabin heat, a coolant warning, or the radiator fan running more than normal. According to Mitsubishi factory diagnostic data, this code indicates an electric water pump malfunction. On many Mitsubishi platforms, this pump supports cooling flow when the engine runs at low speed, during hot soak, or for auxiliary cooling needs. Do not assume the pump has failed. This code points you to a fault in the pump circuit, its power and ground, its control path, or the module logic that monitors pump operation.

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B1115 Quick Answer

B1115 on a 2016 Mitsubishi Outlander means the vehicle detected a malfunction in the electric water pump system. Confirm power, ground, command, and feedback first before replacing the pump.

What Does B1115 Mean?

Official meaning (Mitsubishi-specific): B1115 – Electric water pump malfunction. In practice, the vehicle decided the electric pump did not run when it should, ran when it should not, or operated outside expected behavior. That can reduce coolant circulation in certain operating modes. It can also upset heater performance and thermal management.

What the module checks and why it matters: A Mitsubishi control module monitors the pump circuit for electrical integrity and plausible operation. Depending on platform design, it may watch pump current draw, a feedback signal, or a commanded-versus-actual status. The module sets B1115 when the circuit looks open, shorted, stuck, or implausible during a commanded event. That matters because the DTC does not prove a bad pump. It identifies a suspected trouble area, so you must verify wiring, connectors, and control before parts replacement.

Theory of Operation

Under normal conditions, the Outlander uses an electric water pump to move coolant when extra flow control helps cooling or heater performance. The module commands the pump on and off based on temperature inputs and operating strategy. The pump receives battery power and ground through a dedicated circuit. The control side varies by Mitsubishi platform and may use a switched ground, a duty-controlled driver, or a serial command to an integrated pump module.

B1115 sets when the module commands pump operation and sees an electrical result that does not match expectations. An open power feed can stop pump operation with no load. A short to ground or short to power can force abnormal current or a pump that runs at the wrong time. High resistance in a connector can also cause low pump speed and an implausible response. The same code can set if the module cannot confirm operation due to missing feedback on that platform.

Symptoms

Drivers and technicians usually notice one or more of these issues with B1115:

• Warning message coolant temperature or cooling system warning, depending on cluster configuration
• Overheat tendency temperature rises during idle, traffic, or after shutdown on hot days
• Heater output weak cabin heat at idle or inconsistent heat
• Fan behavior radiator fans run longer or cycle more often than normal
• Stored codes B1115 returns quickly after clearing if the fault stays active
• Coolant smell heat soak and boil-off odor after parking if circulation drops
• Intermittent concern symptoms come and go with bumps, rain, or connector movement

Common Causes

• Blown pump power fuse or open fusible link: An open power feed prevents the electric water pump from running, so the module flags a malfunction.
• High-resistance power or ground path: Corrosion or a loose fastener drops voltage under load and the pump stalls or runs slow.
• Damaged harness near the pump or radiator support: Vibration and heat chafe wiring and create intermittent opens or shorts that mimic pump failure.
• Water intrusion in the pump connector: Coolant splash and road spray wick into terminals and increase resistance or create cross-terminal leakage.
• Short to ground on the pump feed: A rubbed-through feed wire pulls current high, blows protection, or forces the driver circuit to shut down.
• Short to power on the control or feedback circuit: An unintended battery feed back-drives the circuit and the module sees an implausible pump command or status.
• Electric water pump internal mechanical drag: Bearing wear or debris loads the motor, so current draw rises and speed falls until the module sets B1115.
• Electric water pump internal electrical fault: Worn brushes, an open winding, or a failing internal driver stops pump operation even with correct power and ground.
• Control module driver or logic fault: A failing output stage or corrupted logic can stop pump actuation and trigger a malfunction even with a good pump.

Diagnosis Steps

Use a scan tool that can access Mitsubishi body modules and run active tests. Have a DVOM, a fused test light, and back-probing leads. Plan to do voltage-drop testing under load, not continuity checks alone. If available, use a current clamp to compare pump load during commanded operation. Have wiring diagrams and connector views for the Outlander platform.

1. Confirm B1115 on a full scan and record all related DTCs. Save freeze frame data and note battery voltage, ignition state, engine run time, and coolant temperature if listed. Freeze frame shows conditions when the code set. Use a scan tool snapshot later to capture an intermittent drop while you wiggle the harness or command the pump.
2. Check fuses, fusible links, and power distribution feeding the electric water pump circuit. Do a quick visual inspection first for melted fuse tabs, overheated relay sockets, and aftermarket splices. Verify the fuse has power on both sides with the circuit commanded on, not key-on only.
3. Verify module and pump power and ground integrity with voltage-drop testing under load. Command the pump on with an active test or run the condition that normally turns it on. Measure voltage drop on the power side from the battery feed source to the pump B+ terminal. Measure voltage drop on the ground side from the pump ground terminal to battery negative. Keep ground drop under 0.1V with the pump operating.
4. Inspect the pump connector and adjacent harness closely. Look for coolant residue, green terminal corrosion, spread pins, and terminals that back out. Tug-test each wire lightly at the connector. Follow the harness routing where it passes the radiator support and fan shroud. Repair any chafe before deeper testing.
5. Check for shorts to ground or shorts to power on the pump feed and any control or feedback circuits. Unplug the pump and the controlling module connector only if service information allows it. Use the DVOM to verify the circuit does not show battery voltage on a line that should sit at zero when disconnected. Check resistance to ground for a feed that should float with the fuse removed.
6. Use the scan tool to run an electric water pump active test, if supported. Watch commanded state and any available feedback such as pump status or duty command. Listen for pump operation and feel the hoses for flow change. If the scan tool shows the command toggling but the pump never responds, focus on the circuit and the pump load.
7. Verify pump operation at the connector with a loaded test, not an unloaded voltage check. With the pump commanded on, use a fused test light in parallel with the pump feed and ground to confirm the circuit can supply current. If the test light stays bright but the pump does not run, suspect pump internal drag or an internal electrical fault. If the test light dims or flickers, return to voltage-drop and connector checks.
8. If your setup allows it safely, measure pump current draw with a clamp meter during command. Compare current behavior during a good run versus the fault event. A spike with no movement points to mechanical drag. A very low current draw with correct voltage points to an open inside the pump or a broken circuit.
9. Check for intermittent faults with a controlled wiggle test and a scan tool snapshot. Keep the pump commanded on and move the harness at known rub points. Trigger a snapshot when the pump drops out or B1115 flips from pending to confirmed. Remember that freeze frame captured the original set event, while a snapshot captures what you provoke during testing.
10. Clear codes and confirm the repair. Run the same enabling conditions and repeat the active test. Verify B1115 does not return as a pending or stored code. For modules that monitor components continuously, a hard circuit fault often returns immediately at key-on. Treat an immediate return as a wiring, power, ground, or driver issue until proven otherwise.

Professional tip: Don’t trust a clean continuity check on this circuit. The Outlander’s pump load can expose a weak splice or corroded terminal. Voltage drop under command tells the truth. If the pump works on the lift but fails on the road, heat and vibration usually point to a terminal fit issue or a harness rub-through near the front end.

Possible Fixes

• Repair power feed or fuse/relay supply issue: Restore proper power distribution to the pump circuit and verify it carries load during an active test.
• Repair ground path and mounting points: Clean and tighten ground connections, then confirm less than 0.1V drop with the pump operating.
• Repair connector or harness damage: Remove corrosion, replace damaged terminals, and correct chafed wiring with proper sealing and strain relief.
• Replace the electric water pump only after circuit verification: Install a pump after you prove correct power, ground, and command exist at the connector under load.
• Address module output/driver faults after external checks: If the command never leaves the module and all inputs and powers check out, follow Mitsubishi pinpoint tests before module replacement.

Can I Still Drive With B1115?

You can often drive a 2016 Mitsubishi Outlander with B1115 stored, but you should treat it as a time-sensitive cooling-system support fault. Mitsubishi uses electric water pumps for specific cooling tasks that vary by platform and configuration. If that pump does not run, temperatures can rise in the circuit it serves. Watch the temperature gauge closely and stop driving if it climbs, if you smell coolant, or if you see steam. Limit load and avoid long idles until you confirm pump operation. If the vehicle shows overheating, reduced power, or warning messages, tow it. Continued driving during an overheat event can damage the engine and cooling components quickly.

How Serious Is This Code?

B1115 ranges from an inconvenience to a major drivability risk, depending on which electric pump Mitsubishi assigned to the vehicle and when the fault occurs. If the pump supports an auxiliary cooling loop, you may only notice longer warm-up, poor heater output, or intermittent fan operation. When the pump supports critical coolant circulation, the risk jumps fast. The engine can overheat at idle or under load. You can also see fail-safe behavior, like reduced power. Treat any overheating symptom as a safety issue. Confirm the pump receives correct power and ground under command before you replace parts. The DTC points to a malfunction area, not a failed pump.

Common Misdiagnoses

Technicians often replace the electric water pump right away because the description sounds direct. That mistake ignores Mitsubishi’s control logic and the wiring path. A loose connector, coolant intrusion in a pigtail, or a weak ground can mimic a “bad pump” under load. Another common error involves skipping scan-tool active tests and relying only on a resistance check. A pump can ohm “normal” and still stall when commanded. Some shops also miss a related fuse or relay issue because they test it with no load. Verify voltage drop and current flow while commanding the pump. Finally, people confuse an overheat symptom with the root cause and replace thermostats or radiators first.

Most Likely Fix

The most frequent confirmed repair directions involve the pump’s power and ground path, not the pump itself. Start with fixing a poor connection at the pump connector or harness junction. Corrosion, spread terminals, or coolant-wicking into the wires can cause intermittent operation. Next, correct an open fuse link, relay contact issue, or ground point problem found during loaded testing. If the circuit tests clean and the scan tool commands the pump but it does not run or draws abnormal current, then replacing the electric water pump becomes the next logical step. After the repair, road test under conditions that normally command pump operation, since enable criteria vary by Mitsubishi platform.

Repair Costs

Repair cost depends on whether the confirmed root cause is wiring, connector condition, a sensor, a module, or the labor needed to diagnose the fault correctly.