Mitsubishi-specific code — factory diagnostic data| DTC Data Sheet | |
| System | Chassis |
| Standard | Manufacturer Specific |
| Fault type | General |
| Official meaning | Tire ID reception failed – tire 2 |
Definition source: Mitsubishi factory description · Autel MaxiSys Ultra & EV. Diagnostic guidance is based on factory-defined fault logic for this code.
C1921 means the tire pressure system cannot hear one wheel sensor’s ID, so the TPMS warning may stay on and that tire may not show correctly. You can usually still drive, but you lose reliable low-tire warnings for that wheel until you fix it. This is a manufacturer-specific Mitsubishi code, and the exact logic can vary by platform. According to Mitsubishi factory diagnostic data, this code indicates “Tire ID reception failed – tire 2.” In practice, the TPMS ECU expected a specific sensor ID and did not receive it often enough.
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C1921 Quick Answer
On a 2016 Mitsubishi Outlander, C1921 sets when the TPMS system fails to receive the stored tire sensor ID for “tire 2.” The fault points to a missing or unreadable TPMS sensor signal, not a guaranteed bad sensor.
What Does C1921 Mean?
Official definition: “Tire ID reception failed – tire 2.” The TPMS control function detected that it could not receive the identification message it expects from one specific learned sensor position labeled “tire 2.” In real terms, the vehicle cannot reliably monitor that wheel’s tire pressure because it cannot match incoming RF data to the stored ID.
What the module checks and why it matters: The TPMS ECU (or ETACS-integrated TPMS function on some Mitsubishi platforms) looks for a valid RF transmission with the correct sensor ID, timing, and data integrity. When it stops seeing that learned ID, it flags C1921 to steer diagnosis toward the sensor ID, its RF path, the receiver path, or the learned registration state. Do not treat the message as proof the sensor failed. Use it as a suspected trouble area, then confirm with scan data and checks.
Theory of Operation
Under normal operation, each TPMS sensor transmits a unique ID with pressure and temperature data. The Mitsubishi TPMS ECU stores those IDs after registration. It then listens for periodic RF messages and updates pressure display and warning logic.
C1921 sets when the ECU cannot correlate received RF traffic to the stored ID for “tire 2.” A dead sensor battery can cause that. So can an incorrect ID registration, RF interference, a wheel swap without relearn, or a receiver/antenna/wiring problem that reduces reception.
Symptoms
Drivers and technicians usually notice one wheel missing data or a persistent TPMS warning.
- Warning light TPMS lamp stays on or flashes then stays on
- Missing data One tire position does not update on the display or scan tool
- Intermittent operation TPMS works after driving, then drops out again
- Stored DTC C1921 returns quickly after clearing
- No low-pressure alert System may not warn for an actual low tire at that position
- After tire service Concern appears right after rotation, wheel swap, or sensor replacement
- Seasonal wheels Problem starts after installing a second wheel set without registration
Common Causes
- Wrong sensor ID registered to tire 2: The TPMS ECU keeps listening for an ID that never transmits, so it flags an ID reception failure.
- Aftermarket or non-compatible TPMS sensor protocol: A sensor can transmit, but the Mitsubishi receiver cannot decode its format and treats it as not received.
- Low sensor battery or weak RF output: The sensor transmits at reduced strength, so the receiver misses messages during normal driving.
- Interference or RF shielding at the wheel area: Metallic window tint, added electronics, or wheel changes can reduce signal strength and cause intermittent reception loss.
- TPMS receiver/antenna circuit concern: A wiring fault, poor connector fit, or water intrusion at the receiver/antenna reduces sensitivity and drops one wheel’s ID frames.
- Poor power or ground to the TPMS ECU: Voltage drop under load can reduce receiver performance and cause missed ID reception events.
- Harness damage near rear seat, kick panels, or underbody routing: Chafing or pinched wiring can create intermittent opens that show up as a “reception failed” condition.
- Incorrect tire rotation mapping or incomplete relearn after service: The ECU may expect a different wheel position mapping than the vehicle currently uses, depending on Mitsubishi platform logic.
Diagnosis Steps
Tools: a scan tool that can access Mitsubishi TPMS data and perform ID registration, a DMM for voltage-drop testing, and basic hand tools for trim access. A TPMS activation tool helps, but do not rely on it alone. Use service information for connector locations and wiring colors on the 2016 Outlander.
- Confirm C1921 and record DTC status (pending, stored, history). Save freeze frame data. For this chassis code, focus on ignition state, battery voltage, vehicle speed, and any related TPMS or CAN/network DTCs. Freeze frame shows the conditions when the fault set.
- Check for related DTCs first, then run a full module network scan. Verify the TPMS ECU appears on the scan tool list and communicates normally. If the TPMS ECU drops offline, diagnose power/ground or network issues before focusing on any tire ID.
- Inspect fuses and power distribution that feed the TPMS ECU and any TPMS receiver/antenna amplifier used on this Mitsubishi platform. Do this before probing the ECU connectors. Confirm the fuse holds under load and not just visually.
- Verify TPMS ECU power and ground with voltage-drop tests under load. Backprobe at the ECU connector with the ignition ON and the ECU awake. Load the circuit by commanding a data list refresh and performing a function that keeps the ECU active. Accept less than 0.1 V drop on the ground path with the circuit operating.
- Inspect TPMS ECU and receiver/antenna connectors for spread pins, loose fit, corrosion, and water intrusion. Pay attention to any body harness routing near areas that see moisture. Repair terminal tension issues before replacing any module.
- Perform a targeted harness inspection along the likely receiver/antenna and ECU wiring routes. Look for pinch points, prior body repairs, under-car damage, and aftermarket wiring taps. Move the harness while watching live data to try to force an intermittent drop.
- Use the scan tool data list to compare all tire IDs and reception status. Verify whether the ECU shows an ID for “tire 2” and whether it shows “no signal,” “not received,” or similar. Do not assume a wheel corner. Mitsubishi can map tire numbers differently by platform and software.
- If your scan tool supports it, attempt a TPMS ID registration or relearn procedure and follow on-screen prompts. Confirm the procedure completes and the TPMS ECU stores the IDs. If the tool reports “registration failed” for tire 2, treat that as evidence of an ID mismatch, weak transmission, or receiver sensitivity issue.
- Differentiate freeze frame from a scan tool snapshot. Freeze frame captured when C1921 set. Now create a snapshot while driving to catch an intermittent issue. Record vehicle speed, TPMS reception counters if available, and the reception state for the suspect tire number as the concern occurs.
- Eliminate wheel-end causes without guessing. If you have access to a TPMS activation tool, attempt to wake the sensor and confirm it transmits a stable ID. If the tool cannot read the sensor consistently, suspect a weak sensor battery or incompatible sensor. If it reads fine, shift focus back to the vehicle receiver/antenna path and ECU inputs.
- After any repair or correction, clear DTCs and perform a drive cycle that allows TPMS reception to update. Recheck for pending versus confirmed codes. An intermittent fault may first show as pending, then confirm after repeat conditions. Confirm the data list shows normal reception for the tire number tied to C1921.
Professional tip: Do not condemn a TPMS sensor because the warning lamp stays on right after service. Mitsubishi TPMS often needs time and driving to update reception. Use live data reception status and a snapshot during the test drive. If only one tire number fails while others update, chase ID registration accuracy and receiver sensitivity before replacing parts.
Possible Fixes
- Correct the registered TPMS IDs and complete the Mitsubishi relearn/registration procedure for the Outlander platform.
- Repair power or ground voltage-drop issues feeding the TPMS ECU or receiver/antenna circuit.
- Clean, tighten, or repair TPMS ECU and receiver/antenna connector terminals affected by corrosion or poor pin fit.
- Repair harness damage, chafing, or intermittent opens/shorts in the TPMS receiver/antenna or ECU wiring path.
- Replace the TPMS sensor only after confirming it fails to transmit reliably or it does not match the required protocol.
- Replace a failed TPMS receiver/antenna component only after circuit integrity checks and confirmed loss of sensitivity.
Can I Still Drive With C1921?
You can usually drive a 2016 Mitsubishi Outlander with C1921, but you should treat it as a safety-system warning. This code means the TPMS control unit cannot receive the tire pressure sensor ID for “tire 2.” That does not change braking, steering, or engine control. It does remove your early warning for a low tire on that wheel position. Do not rely on the dash to catch a slow leak. Manually check all tire pressures with a quality gauge before driving and at least weekly until you fix the cause. If the TPMS warning flashes first, then stays on, prioritize diagnosis soon because the system often cannot trust any wheel data during the fault.
How Serious Is This Code?
C1921 ranges from an inconvenience to a real safety risk, depending on how you use the vehicle. For normal commuting, the main impact is the loss of TPMS warning coverage for the affected tire ID. That becomes more serious at highway speeds, in heavy loads, or in extreme temperatures, where pressure changes quickly. The Outlander still drives normally, but you lose a layer of protection against underinflation, overheating, and tire failure. Take it seriously if you tow, carry passengers often, or see frequent punctures. Treat it as urgent if you also have vibration, a pull, visible tire damage, or repeated pressure loss, because those issues demand immediate tire inspection.
Common Misdiagnoses
Technicians often replace a sensor immediately because the code names a “tire,” then the code returns. C1921 only tells you the TPMS module failed to receive an ID message for tire 2. It does not prove a dead sensor. The most common missed steps include skipping a TPMS activation test, ignoring wheel swaps or a recently installed spare, and not verifying the correct sensor frequency and ID format for Mitsubishi. Another frequent mistake involves relearn assumptions. Some Outlander TPMS systems need a specific registration routine after sensor changes. Shops also overlook simple RF blockers, like certain aftermarket window tint types, dash cams, or cargo-mounted devices near the receiver path. Corrosion at the TPMS receiver or module connector can mimic a bad sensor. Confirm RF activity and module inputs before buying parts.
Most Likely Fix
The most frequently confirmed repair direction for C1921 involves restoring the TPMS system’s ability to recognize and store the correct sensor ID for the “tire 2” position. Start with a sensor ID activation test at that wheel and compare it to scan-tool TPMS data. If the module never sees an ID, correct the cause you can prove: repair damage at the valve stem area, correct an incompatible sensor, or fix a wiring/connector issue at the TPMS receiver/module if equipped. If the module sees an ID but still flags reception failed, perform the Mitsubishi TPMS ID registration procedure and then road test long enough for the monitor to run. The exact enable criteria varies by platform, so confirm with service information.
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.
| Repair Type | Estimated Cost |
|---|---|
| Basic DIY inspection | $0 – $50 |
| Professional diagnosis | $100 – $180 |
| Wiring / connector repair | $80 – $350+ |
| Component / module repair | $120 – $600+ |
Key Takeaways
- C1921 on Mitsubishi: The TPMS system failed to receive the tire pressure sensor ID for “tire 2.”
- It is not a confirmed bad sensor: The DTC points to a reception/recognition problem, not a guaranteed sensor failure.
- Verify RF and registration first: Use a TPMS tool and scan-tool data to confirm the module can “hear” the sensor.
- Check recent work: Tire rotations, wheel swaps, aftermarket sensors, and relearn steps drive many repeat faults.
- Drive with caution: The vehicle drives normally, but you lose low-pressure warning coverage.
FAQ
Does “tire 2” tell me which corner sensor failed?
Not reliably. Mitsubishi uses “tire 2” as an indexed position inside the TPMS logic, and the mapping can change after rotations or registration. Use scan-tool TPMS data to see which sensor ID the module assigns to each position. Then confirm the physical wheel by activating each sensor with a TPMS tool.
Can my scan tool still communicate with the TPMS module, and why does that matter?
Yes, it usually can, and that matters a lot diagnostically. If the scan tool communicates, you can read live TPMS data, stored IDs, and registration status. That helps separate an RF reception problem from a module power/ground issue. If you cannot communicate, check TPMS module fuses, grounds, and network integrity before chasing sensors.
How do I confirm the problem before replacing any TPMS sensor?
Trigger the suspect wheel sensor with a TPMS activation tool and watch the scan tool for a received ID change or signal update. If the tool reads the sensor but the vehicle does not, focus on module reception, antenna/receiver path, interference, or wrong sensor type. If neither tool can read it, inspect the valve stem area and sensor damage.
After I repair it, how long do I need to drive to prove the fix?
Clear codes only after you complete repairs and registration. Then drive long enough for the TPMS to complete its reception checks and update IDs. The needed speed, time, and temperature conditions vary by Mitsubishi platform. Use a scan tool to confirm the DTC stays cleared and that each tire position shows a valid sensor ID and current pressure.
Does this code mean the TPMS module needs programming or replacement?
Not as a first move. Most C1921 cases trace to sensor ID registration, incompatible sensors, or reception issues. If you prove good sensor transmission and correct registration, then verify module power, grounds, and connector condition under load. When replacement becomes justified, use Mitsubishi-capable scan equipment to perform any required ID registration and system setup afterward.