CISPR, IEC
CISPR 12
Vehicles, boats and devices with internal combustion engines or traction batteries – Radio disturbance characteristics – Limits and methods of measurement for the protection of off-board receivers
CISPR 12:2025 establishes radiated emission limits and measurement methods from 30 MHz to 1,000 MHz to protect off-board radio receivers. It addresses vehicles, boats, engine-powered equipment, and applicable electric propulsion and charging configurations.
Scope
CISPR 12 specifies radiated electromagnetic disturbance limits and measurement methods for vehicles, boats, and engine-powered equipment. Its purpose is to protect radio receivers located outside the vehicle or equipment, particularly in residential environments.
The standard covers 30 MHz to 1,000 MHz and applies to vehicles powered by internal combustion engines, electric propulsion, or a combination of both.
Excluded applications: Aircraft, household appliances, railway traction systems, and incomplete vehicles are outside the scope of this edition. Measurements while a vehicle is connected to the electrical mains for charging are also excluded.
CISPR 12 versus CISPR 25: CISPR 12 addresses interference to external receivers, whereas CISPR 25 addresses interference to receivers installed onboard the same vehicle.
Applicable Products and Devices
CISPR 12 applies to the following categories of equipment within the scope of the standard:
Passenger and Commercial Vehicles: Cars, trucks, buses, and other road vehicles powered by combustion engines, electric motors, or hybrid propulsion systems.
Motorcycles and Off-Road Vehicles: Mopeds, snowmobiles, agricultural machinery, earth-moving equipment, mining machinery, and material-handling vehicles.
Marine Equipment: Boats with internal combustion or electric propulsion, subject to the specific marine test arrangements.
Engine-Powered Devices: Snow blowers, irrigation pumps, air compressors, chainsaws, landscaping machinery, and other applicable engine-driven equipment.
Important: CISPR 12 is primarily a complete-vehicle or complete-equipment emission standard. It does not establish the component-level conducted and radiated emission classes specified by CISPR 25.
Markets and Regulatory Context
CISPR 12 is an internationally recognized automotive electromagnetic compatibility standard used to evaluate radio-frequency disturbances emitted by complete vehicles and engine-powered equipment.
Automotive Type Approval: CISPR 12 measurement principles are relevant to automotive radiated emission assessments. However, compliance with CISPR 12 alone does not establish conformity with all requirements of UNECE Regulation No. 10.
Vehicle Manufacturers: OEMs may specify CISPR 12 measurements for vehicle qualification, development testing, production verification, or investigation of excessive radiated emissions.
International Markets: The applicable edition, test distance, acceptance limits, and regulatory requirements must be confirmed for the intended destination market and approval program.
Key distinction: CISPR 12 addresses unintentional electromagnetic disturbances. Requirements for intentional radio transmissions and their spurious emissions are evaluated under applicable radio regulations.
Principal Tests and Requirements
CISPR 12 establishes radiated emission measurements from 30 MHz to 1,000 MHz. Unlike CISPR 25, this edition does not specify separate conducted emission tests for automotive components.
Radiated Emissions – Engine Running
The vehicle or equipment is operated under the specified engine-running conditions. Emissions are assessed against the applicable peak or quasi-peak limits.
Radiated Emissions – Key-On, Engine-Off
The vehicle is evaluated with the ignition or electrical system activated and the engine stopped. Emissions are assessed against the average detector limits.
Measurement Site and Antenna Requirements
Measurements are performed at a specified antenna distance of 10 m or, under the conditions established by the standard, 3 m. Both horizontal and vertical antenna polarizations are evaluated.
Important: An absorber-lined shielded enclosure (ALSE) may be used when its results can be correlated with those obtained at the specified outdoor test site.
Frequency Ranges and Test Levels
CISPR 12 specifies radiated emission measurements over 30 MHz to 1,000 MHz. The measurement configuration depends on the test distance, detector type, antenna polarization, and operating condition.
| Parameter | Requirement |
|---|---|
| Frequency range | 30–1,000 MHz |
| Standard antenna distance | 10 m |
| Alternative antenna distance | 3 m, subject to specified conditions |
| Antenna height at 10 m | 3.00 m, tolerance +0.05 / -0.05 m |
| Antenna height at 3 m | 1.80 m, tolerance +0.05 / -0.05 m |
| Antenna polarization | Horizontal and vertical |
| Quasi-peak receiver bandwidth | 120 kHz |
Measurement Distance: For the 2025 edition, the specified 3 m emission limits are 10 dB higher than the corresponding 10 m limits. The applicable test-site and antenna positioning requirements must also be satisfied.
Measurement Instrumentation: The measuring receiver must meet the relevant CISPR 16 requirements. The measurement noise floor must be at least 6 dB below the applicable emission limit.
Limit Overview
CISPR 12 specifies frequency-dependent radiated emission limits for complete vehicles, boats, and applicable engine-powered devices. Unlike CISPR 25, it does not use Class 1 to Class 5 emission categories.
The applicable limit depends on the measurement frequency, detector type, receiver bandwidth, antenna distance, and operating condition.
Peak and Quasi-Peak Limits – 120 kHz Bandwidth
| Frequency Range | 10 m Quasi-Peak | 10 m Peak | 3 m Quasi-Peak | 3 m Peak |
|---|---|---|---|---|
| 30–75 MHz | 34 | 54 | 44 | 64 |
| 75–400 MHz | 34 + 15.13 log10(f/75) | 54 + 15.13 log10(f/75) | 10 m limit + 10 | 10 m limit + 10 |
| 400–1,000 MHz | 45 | 65 | 55 | 75 |
Units: All limits are expressed in dB(uV/m). In the equations, f is the measurement frequency in MHz.
Reference: CISPR 12:2025, Figure 2. The peak limits shown use a 120 kHz bandwidth. The standard also provides a separate peak limit option using a 1 MHz bandwidth.
Average Detector Limits
| Frequency Range | 10 m Average | 3 m Average |
|---|---|---|
| 30–230 MHz | 30 dB(uV/m) | 40 dB(uV/m) |
| 230–1,000 MHz | 37 dB(uV/m) | 47 dB(uV/m) |
Reference: CISPR 12:2025, Figure 3.
Compliance Requirements
Key-On, Engine-Off: The equipment must comply with the applicable average detector limits.
Engine Running: The equipment must comply with the applicable peak or quasi-peak detector limits.
Overall Compliance: Both applicable operating-condition assessments must pass, subject to the exceptions and alternative provisions specified in the standard.
Equipment Configuration and Operating Modes
CISPR 12 requires the vehicle or equipment to be operated under defined conditions to obtain reproducible radiated emission measurements. Engine operation, electrical loads, antenna position, and measurement site characteristics can influence the recorded emissions.
Key-On, Engine-Off Configuration
The vehicle electrical system is activated while the engine remains stopped. This condition is used to evaluate disturbances from onboard electronic systems against the applicable average emission limits.
Engine-Running Configuration
The vehicle or equipment is operated at the engine speeds and conditions specified in the standard. This measurement evaluates emissions from ignition systems, rotating electrical machinery, and other systems operating during propulsion.
Antenna Position and Test Site
Both horizontal and vertical polarizations must be measured. Antenna distance, height, and the position of the vehicle relative to the antenna must follow the applicable test arrangement.
Outdoor Test Site: The measurement area must satisfy the specified clearance and ambient-noise requirements.
Absorber-Lined Shielded Enclosure: Indoor testing is permitted when correlation with the specified outdoor test site has been established.
Test Documentation: The report should identify the vehicle configuration, operating conditions, measurement distance, antenna polarization, detector, emission results, and applicable limits.
Engineering and Pre-Compliance Guidance
Excessive radiated emissions can originate from multiple electrical systems operating simultaneously. The dominant emission source may change with engine speed, electrical loading, or vehicle operating mode.
Ignition System Interference
Spark ignition systems can generate repetitive broadband electromagnetic disturbances. Ignition cables, spark plugs, suppression components, and grounding arrangements influence the resulting emissions.
Electric Motor and Inverter Emissions
Electric propulsion systems can generate RF disturbances through high-speed switching and common-mode currents. Power cable shielding, inverter enclosure bonding, and motor connections can influence radiated emission levels.
Vehicle Wiring and Grounding
Vehicle harnesses can act as radiating structures when RF currents propagate along cables. Cable routing, grounding impedance, connector design, and shielding termination can affect emissions measured outside the vehicle.
Diagnosing Emission Failures
Frequency Correlation: Compare emission peaks with switching frequencies, clock harmonics, and engine-related disturbance patterns.
Operating Mode Comparison: Identify whether emissions change between key-on/engine-off and engine-running conditions.
Source Isolation: Use near-field probes, current probes, and controlled subsystem operation to identify the dominant interference source.
Corrective Action Verification: Confirm that shielding, grounding, filtering, or ignition suppression modifications reduce the measured emissions under the required operating conditions.
Engineering Consideration: Corrective actions should be verified using the same vehicle configuration and operating conditions that produced the original failure.
Testing and Compliance Support
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