Poor Car Radio Reception? Causes and Fixes
Poor car radio reception usually comes down to the aerial connection. After a new stereo, the most common causes are a missing antenna adapter or an aerial amplifier that is no longer getting power. Interference from cheap chargers and LED bulbs, a damaged aerial, or a Japanese radio that cannot tune the whole NZ FM band are the other usual suspects.
Reception got worse after a new stereo
- A missing or wrong antenna adapter: many cars, including Japanese imports and many European cars, use a different aerial plug from aftermarket units. Without the right adapter, the aerial is barely connected.
- An unpowered aerial amplifier: cars with a roof, glass or short aerial often have a small amplifier that needs 12V. The head unit's blue or blue and white turn-on wire should feed it. If it is not connected, reception drops sharply.
Our wiring harness guide explains the adapters a new stereo needs.
Other causes
- Interference: cheap USB chargers, dash cam power leads and LED bulbs can add hiss or buzz to FM. Unplug them one at a time to find the culprit.
- A loose or damaged aerial: check the mast is tight, and look for broken lines on a glass aerial.
- A Japanese radio: radios built for Japan cover a lower FM band, so some NZ stations cannot be tuned at all. See the FM band expander guide.
- Location: hills, tunnels and parking buildings weaken any signal.
When to get help
If reception dropped right after a stereo was fitted, the aerial connection or amplifier power is the first thing to check. We fit head units with the right aerial adapter and power lead: see head unit installation.
Frequently asked questions
Why is my radio reception bad after installing a new stereo?
Usually the antenna adapter is missing or wrong, or the aerial amplifier is not powered by the head unit's turn-on wire.
Can a USB charger affect car radio reception?
Yes. Cheap chargers and some LED bulbs create electrical noise that FM picks up as hiss or buzz.
Why can I not find some NZ stations on my Japanese radio?
Japanese radios cover a lower FM band. A band expander or a new NZ-ready head unit fixes it.