Code
P1221
MITSUBISHI
P — Powertrain
ETV motor feedback
Views:
UK: 13
EN: 34
RU: 25
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in the ETV motor/feedback circuit
- Corroded, loose or damaged connector at the throttle body or ECU
- Faulty ETV motor or integrated position sensor
- Stuck/throttled valve (carbon buildup, mechanical binding)
- Blown fuse or poor power/ground to the throttle assembly
- ECU internal fault or intermittent electronic failure
Symptoms
- Check Engine Light (MIL) illuminated
- Reduced engine power / limp-home mode
- Poor throttle response, delayed acceleration
- Irregular or rough idle
- Engine stalls or surges during idle or low speed
- Inability to command throttle plate via scan tool
What to check
- Read stored freeze frame and live data with a capable scan tool; note ETV feedback PID and diagnostic codes
- Attempt to command ETV open/close from the scan tool and observe feedback change
- Visually inspect throttle body connector and ECU connector for corrosion, bent pins or loose terminals
- Check fuses and relays related to throttle control and engine management
- Back-probe the ETV feedback, reference and ground circuits; verify reference voltage (~5V) and ground continuity with ignition ON
- Wiggle wiring harness while monitoring live data for intermittent faults
Signal parameters
- Reference voltage to sensor: ~5.0 V (ignition ON)
- Feedback/position sensor voltage: typically ~0.5–4.5 V depending on throttle position (closed low, open high)
- Motor control: ECU may use PWM drive — frequency typically tens to a few hundred Hz (refer to service manual)
- Ground should be near 0 V; no high resistance
Diagnostic algorithm
- Retrieve and record all codes and freeze-frame data. Clear codes and attempt to reproduce fault with a controlled drive or scan-tool commanded ETV cycles.
- With ignition ON (engine off), verify reference voltage (~5 V) and ground at the throttle body connector. Back-probe signal while manually moving the throttle (if safe) or using the scan tool to command position; confirm the feedback voltage moves smoothly without dropouts.
- Visually inspect connectors and wiring for damage, corrosion, heat damage or water ingress. Repair any damaged wiring or connectors.
- Check continuity and resistance of signal and ground circuits between the throttle body connector and ECU; repair any open/short circuits. Verify power feed and fuses to the throttle assembly.
- Use a scan tool to command the ETV open/close and observe the feedback. If commanding produces no movement or incorrect feedback, isolate whether the motor or sensor is at fault by measuring motor coil resistance and applying bench tests as per service manual.
- Inspect throttle body mechanically for seized or sticky valve; clean if necessary following manufacturer procedure. Reassemble and recheck feedback and operation.
- If wiring and throttle body tests are good but fault persists, consider ECU diagnostics or replacement as a last step. After repairs, clear codes and perform a test drive to confirm repair.
- Note: Refer to the vehicle-specific service manual for exact voltage, resistance specs and safety precautions before applying power or removing components.
Likely causes
- Corroded/loose connector at throttle body
- Open or shorted signal wire between throttle body and ECM
- Failed ETV motor or feedback potentiometer/sensor
- Valve binding from carbon deposits or foreign material
- Poor ground at throttle body or ECU
Fault status
Status
ETV motor feedback circuit malfunction — ECM detected abnormal or missing feedback from the Electronic Throttle Valve motor/position sensor. May cause reduced power (limp mode) and degraded throttle control.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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