OBD Guide
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P1621

Control Module Long Term Memory Performance Condition

P1621 is an OBD-II diagnostic trouble code meaning: Control Module Long Term Memory Performance Condition. Common causes: engine control unit malfunction, ecu power problems. Estimated repair cost: $56–278.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$56–278 (est.)

Symptoms

  • Unstable engine operation
  • Increased fuel consumption
  • Check Engine Light Illuminates
  • Losing saved settings (for example, radio stations)
  • Problems starting the engine

Causes

  • Engine control unit malfunction
  • ECU power problems
  • Short circuit in ECU circuit
  • Corrosion of control unit contacts
  • Software error in ECU

How to Fix

  1. Check the supply voltage of the control unit
  2. Inspect ECU connectors and wiring harness
  3. Check for corrosion on contacts
  4. Flash or replace the control unit
  5. Reset the error and check for its reappearance

Related codes

P0601P0602P0603

Error P1621 by Vehicle Brand

BuickCadillacChevroletGMGMCMazdaOldsmobileSaturnVolkswagen

FAQ

What does the P1621 code mean?

P1621 is an OBD-II diagnostic trouble code that indicates: Control Module Long Term Memory Performance Condition

What causes a P1621 error code?

The most common causes of P1621 include: Engine control unit malfunction; ECU power problems; Short circuit in ECU circuit; Corrosion of control unit contacts.

How do I fix a P1621 diagnostic trouble code?

To fix P1621: Check the supply voltage of the control unit. Inspect ECU connectors and wiring harness. Check for corrosion on contacts. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1621?

Yes, but get it checked soon

How much does it cost to fix P1621?

The estimated repair cost for P1621 is $56–278. Actual cost depends on your vehicle, location, and labor rates.

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