OBD Guide
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P1638

Generator 'F' Terminal Circuit Conditions

P1638 is an OBD-II diagnostic trouble code meaning: Generator 'F' Terminal Circuit Conditions. Common causes: damaged wiring to the generator, faulty generator. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Check Engine Light Is On
  • Low battery charge
  • Flashing headlights when the engine is running
  • Unstable operation of electrical equipment
  • Low battery

Causes

  • Damaged wiring to the generator
  • Faulty generator
  • Short circuit in the circuit
  • Poor contact at terminals
  • Engine control unit malfunction

How to Fix

  1. Check the condition of the wiring to the generator
  2. Check the voltage at the generator terminals
  3. Test the operation of the generator
  4. Check connections at battery terminals
  5. Replace the generator if necessary

Related codes

P0620P0622P0562

Error P1638 by Vehicle Brand

BMWBuickCadillacChevroletGMGMCJaguarOldsmobileSaturnVolkswagen

FAQ

What does the P1638 code mean?

P1638 is an OBD-II diagnostic trouble code that indicates: Generator 'F' Terminal Circuit Conditions

What causes a P1638 error code?

The most common causes of P1638 include: Damaged wiring to the generator; Faulty generator; Short circuit in the circuit; Poor contact at terminals.

How do I fix a P1638 diagnostic trouble code?

To fix P1638: Check the condition of the wiring to the generator. Check the voltage at the generator terminals. Test the operation of the generator. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1638?

Yes, but get it checked soon

How much does it cost to fix P1638?

The estimated repair cost for P1638 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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