POWERSTROKE-P0128 moderate Power Stroke ›

Coolant Thermostat Below Regulating Temperature

The POWERSTROKE-P0128 (Power Stroke) diesel fault code means: Coolant Thermostat Below Regulating Temperature. This is a moderate severity code.

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Keep driving?
Yes, but fix soon
DIY difficulty
intermediate
Estimated cost
$150-$400
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What Are the Symptoms of POWERSTROKE-P0128?

  • Slow warm-up
  • Heater blows cool
  • CEL
  • Lower MPG in winter

What Causes POWERSTROKE-P0128? (Most Likely First)

  • Stuck-open thermostat(s) Very Likely
  • Failed ECT sensor reading low Likely

Can I Still Drive with POWERSTROKE-P0128?

Yes, but fix soon. POWERSTROKE-P0128 is rated moderate severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring it.

Frequently Asked Questions

What is P0128 on a 6.7L Power Stroke (Scorpion)?

P0128 on a 6.7L Power Stroke (Scorpion) (2011-present) indicates: Coolant Thermostat Below Regulating Temperature. This is a known diagnostic trouble code on this engine family and typically points to the causes listed above.

Can I drive with P0128 on my Power Stroke?

Yes, you can generally drive with this code, but diagnose it soon to prevent further damage.

How much does it cost to fix P0128?

Repair cost is typically $150-$400 depending on the underlying cause and whether you DIY or use a shop. Diagnostic time alone runs $100-$180 at most independent diesel shops.

Mechanics Guide Step-by-step diagnosis

How Do You Diagnose POWERSTROKE-P0128?

  1. Monitor ECT warm-up time; spec is <10 min.

  2. Replace thermostats (6.7L has two stats).

Sources 1

This page is built from documented references. Verify against your own service info before repair work.

  • SAE J2012Diagnostic Trouble Code Definitions (defines P0128 as a generic OBD-II code)

P0128 on Other Platforms

The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown:

Gas / Automotive (OBD-II) Generic OBD-II definition for P0128 Duramax moderate Coolant Thermostat Below Regulating Temperature PACCAR minor Coolant Temp Below Thermostat Regulating Temperature

Which Vehicles Commonly Get POWERSTROKE-P0128?

  • 2011-present Ford F-250 Super Duty 6.7L Power Stroke
  • 2011-present Ford F-350 Super Duty 6.7L Power Stroke
  • 2011-present Ford F-450/F-550 Super Duty 6.7L Power Stroke
  • 2015-2019 Ford F-650/F-750 6.7L Power Stroke

Explore More

More Power Stroke codes → Diesel home All diesel codes Heavy-duty Guides

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