Pre-Certified Modules & Host Device Testing

What pre-certified modules are

A pre-certified RF module is a self-contained transmitter component that has already obtained its own FCC ID under 47 CFR 15.212. When you integrate one into your product, the module's FCC grant covers the intentional radio emissions. Your host product only needs unintentional emissions testing (Part 15 Subpart B), not full intentional radiator certification.

This is how the vast majority of IoT and smart home products reach market. Instead of designing custom RF circuitry and going through $8,000 -- $20,000+ in full intentional radiator testing, you drop in a module and spend $2,500 -- $5,500 on host-level EMC testing.

Popular pre-certified modules

The 8 requirements for modular approval

Under 15.212(a), a module receives full (unrestricted) modular approval if it meets all eight criteria:

1. Own RF shielding on radio elements
2. Buffered modulation/data inputs -- ensures Part 15 compliance regardless of host signal
3. On-board power supply regulation -- not reliant on host power quality
4. Permanently attached antenna or unique connector -- no standard SMA/U.FL allowed (or must use proprietary coupler)
5. Tested as a stand-alone unit -- not inside a specific host
6. Labeled with own FCC ID -- visible after installation, or host product references it
7. Complies with all applicable rule parts -- Part 15C, Part 24, Part 27, etc.
8. RF exposure compliance -- SAR/MPE evaluation per 2.1091/2.1093

Modules that cannot meet all eight criteria receive limited modular approval under 15.212(b), with restrictions noted on the grant (specific antenna types, host configurations, installation conditions).

Detailed guidance is in KDB 996369 (D01 for general requirements, D04 for host integration, D05 for split modules).

What host-level testing you still need

Even with a fully pre-certified module, your host product requires:

Always required

• Part 15B unintentional emissions testing -- radiated and conducted emissions from your digital circuitry, power supply, display, clocks, and all non-radio components. This is the minimum test scope for any host.

Required in specific cases

• RF exposure re-evaluation if the antenna placement or device-to-body distance differs from the module's original grant conditions. Per KDB 447498, you need either an SAR test, an MPE calculation, or a KDB 447498-compliant exclusion analysis.

• Additional RF measurements per KDB 996369 D04 if you modified the antenna configuration, changed the antenna type, or if the module has limited (not full) modular approval.

• Full intentional radiator certification if your host contains additional intentional radiators not covered by the module's grant -- for example, a separate NFC antenna, a custom sub-GHz radio, or a different WiFi radio.

Typical test plan for a host with pre-certified module

When a pre-certified module is not enough

A module does not save you from full certification in these scenarios:

1. You modified the module's antenna. If you replaced the module's antenna with your own design, changed the antenna cable length, or altered the ground plane geometry in a way that could affect RF performance, the module's grant conditions may no longer apply. You may need additional RF testing or, in some cases, full certification.

2. The module has limited modular approval with restrictions you cannot meet. Check the module's FCC grant notes carefully. Some grants specify exact antenna types, maximum cable lengths, or minimum separation distances. Violating any restriction voids the modular approval for your configuration.

3. Your host has additional transmitters. A Part 15B SDoC only covers the host's unintentional emissions. If your product also includes a custom sub-GHz radio, NFC at regulated power levels, or any other intentional transmitter without its own FCC ID, you need separate certification for those.

4. You are using a chip-down design, not a module. Soldering an ESP32-S3 chip directly to your PCB (without the module's shielding, power regulation, and antenna matching) is not the same as using the ESP32-S3-WROOM module. The chip does not have modular approval. You need full intentional radiator certification.

5. Co-location interference. When multiple transmitters operate in the same device (common with WiFi + BT + Zigbee hubs), simultaneous transmission testing may be required even if each radio has its own module grant. Per KDB 616217, the TCB evaluates whether simultaneous operation affects compliance.

Cost and time savings

At 10,000 units, the BOM premium of a module ($29,000 extra) is roughly offset by certification savings ($5,500 -- $14,500) and engineering NRE savings. Below 50,000 units, modules almost always win on total cost. Above 100,000 units, the per-unit BOM savings of chip-down designs start to justify the upfront certification investment.

For a startup shipping its first hardware product, the answer is nearly always: use a pre-certified module. You can always move to chip-down in v2 once you have volume and revenue to justify the RF engineering and certification cost.

How to verify a module's FCC status

Before selecting a module, confirm its certification:

1. Find the module's FCC ID in the datasheet or on the module itself
2. Search the FCC EAS database or use MarkReady Search
3. Check the grant date, granted frequencies, and power levels
4. Read the grant notes for any limited modular approval conditions
5. Verify the grant is still active (no termination or revocation)

Pay particular attention to KDB 996369 D04 host integration requirements listed in the grant. These define what you can and cannot change about the antenna configuration.

Labeling with a module's FCC ID

Your host product must reference the module's FCC ID. Two approaches:

• Module FCC ID visible through host enclosure: If the module's label is visible without disassembly, no additional FCC ID labeling is needed on the host.
• Module FCC ID not visible: The host must display "Contains FCC ID: XXXXX-YYYYYY" on its own label.

See our FCC Label Requirements guide for full labeling rules.