OBD Guide
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U1421

Implausible Ignition Key Off Time Received

U1421 is an OBD-II diagnostic trouble code meaning: Implausible Ignition Key Off Time Received. Common causes: ecm power problems, ecm malfunction. Estimated repair cost: ~$278.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
~$278 (est.)

Symptoms

  • Check Engine light comes on
  • Incorrect operation of the EVAP system
  • Errors in other systems that depend on downtime
  • Problems starting the engine (in rare cases)

Causes

  • ECM power problems
  • ECM malfunction
  • Wiring harness damage
  • Problems with communication between modules
  • CAN bus malfunctions

How to Fix

  1. Check error codes in other modules
  2. Check the integrity of the wiring harness
  3. Check ECM power and ground
  4. Scan the CAN bus for errors
  5. Replace ECM if necessary

Related codes

U1401U1420U1422

FAQ

What does the U1421 code mean?

U1421 is an OBD-II diagnostic trouble code that indicates: Implausible Ignition Key Off Time Received

What causes a U1421 error code?

The most common causes of U1421 include: ECM power problems; ECM malfunction; Wiring harness damage; Problems with communication between modules.

How do I fix a U1421 diagnostic trouble code?

To fix U1421: Check error codes in other modules. Check the integrity of the wiring harness. Check ECM power and ground. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U1421?

Yes, but get it checked soon

How much does it cost to fix U1421?

The estimated repair cost for U1421 is ~$278. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat