🚀 New launch promo — 10% off orders over $300. Use code LAUNCH10
Bubbles Supply
Not sure which part you need? Upload a photo and we'll find it. →
MS5012U Control Pack X300736 - Bubbles Supply

MS5012U Control Pack X300736

Part #: X300736

$1680.93
In stock — ships today
Qty
🔒 Secure checkout↩️ 30-day returns✅ 1-year warranty
Add to B2B order list

Not sure this fits?

Send us a photo of your old part — we'll confirm the right replacement before you order.

Upload a Photo
1-year warrantySame-day ship before 3pm CTPerfect Fit Guarantee30-day returns

About this control pack

The MS5012U Control Pack with 4.0 kW Heater is a genuine OEM replacement part designed for Master Spa hot tubs experiencing heater failures, HH error codes, or OH error messages. This complete control system integrates heating elements and electronic controls in one unit, eliminating the guesswork when troubleshooting temperature-related issues in your spa.

Built to Master Spa's exact specifications, this control pack delivers reliable 4.0 kW heating power to restore your spa's performance. At Bubbles Supply, we guarantee an exact fit for compatible Master Spa models and ship the same day for minimal downtime. Every unit includes our comprehensive 1-year warranty for complete peace of mind. Verify your current control pack's part number and electrical requirements before installation, as proper electrical connections are essential for safe operation.

Exact part number

X300736

Save this for ordering or warranty claims

Also known as / Replaces

This part replaces or is interchangeable with:

  • 4.0 kW Heater Assembly
  • Control Pack
  • Master Spa Control Pack
  • MS5012U

Looking for an older part number? Check our supersession lookup tool

Common symptoms this part fixes

If your spa is showing any of these signs, this part is likely your fix:

  • HH error code displayed on topside panel
  • OH (overheat) error code not clearing
  • Spa not reaching or holding set temperature
  • Heater not firing — cold water despite pump running
  • Control pack cycling off unexpectedly
  • Spa locked out due to repeated high-limit trips

Not sure if this is your problem? Try our diagnostic centre or .

Before you buy — quick checklist

  • Match the part number on your existing control pack label before ordering — X300736 must appear on the unit
  • Verify your spa's voltage and amperage requirements match this control pack's electrical specs
  • Confirm your Master Spa model year and series — control packs are not universally interchangeable across generations
  • Check whether your HH or OH error is heater-related or sensor-related before replacing the full control pack
  • Inspect wiring harness connectors on your current pack for corrosion or burn damage — address wiring issues before installing a new unit

Reading the checklist now prevents 90% of returns. Worth the 60 seconds.

Install difficulty: Hard — Technician recommendedTypically 60-120 minutes

Warranty

1 year manufacturer warranty against defects

Covers manufacturing defects. Does not cover improper installation, normal wear, or accidental damage.

Warranty claims: warranty@bubblessupply.com

Perfect Fit Guarantee

Ordered with our help and the part doesn't fit? Contact us before installation. We'll resolve it with an exchange, replacement recommendation, or return approval.

Learn about our Perfect Fit Guarantee →

Shipping

We ship across the US and Canada. US orders ship from our US warehouse to US customers; Canadian orders ship from our Canadian warehouse to Canadian customers — no cross-border shipping, no surprise duties. In-stock orders placed before 3pm CT ship same day. Standard shipping $9.95 flat rate. Free shipping on orders over $200. Express options available at checkout.

Returns

30-day hassle-free returns on unused parts in original packaging. Contact us before returning to receive your RMA number.

Frequently asked questions

Check the Compatibility section above to confirm fitment for your spa brand and model. If your model is not listed, use our fitment selector at /pages/find-my-part or ask our parts AI for a personalized recommendation.

In-stock orders placed before 3pm CT ship the same day. You will receive tracking information by email as soon as your order ships.

We accept returns within 30 days of delivery for unused items in original packaging. Email returns@bubblessupply.com with your order number to start a return. Installed electrical parts cannot be returned for safety reasons.

Yes, all new parts come with a 1-year warranty against manufacturing defects. Warranty does not cover damage from improper installation or normal wear and tear.

Customer reviews

AI Fitment Assistant

Tell us your spa model and we will confirm this part fits before you buy.

🔒 Secure checkout · SSL encrypted·🇺🇸🇨🇦 Serving the US and Canada·↩️ 30-day hassle-free returns·📦 Same-day fulfillment