Your car amplifier is a key component to your vehicle’s audio system performance. If problems or issues arise, you want to know the cause and the way to repair it, or at least where you can get it repaired. Car audio systems use individual audio components, which are often DIY installed. This makes your car stereo system different than home audio equipment, which is usually sold as a cohesive package that is powered by a wall outlet.

We get many questions about car amplifier repair, so we created this article to answer the inquiries we hear most frequently.

What causes an amp to cut out?

Several possible problems cause a car amplifier to shut off. The first step is to examine the amp for a warning indicator light. If your car amplifier has a protection mode LED, and the LED stays illuminated, then the amp is in “protection” mode. The following reasons might cause protection mode:

• Check for blown speakers. When a speaker blows, its voice coil can short circuit or have much lower impedance. Unplug all speaker wires from the amp. If the protection light turns off, a speaker is most likely the source of your problem. Check each speaker connected to the amp to make sure it is working properly.
• Check the RCA signal cables. They might be grounded out or faulty. To test this, you can simply connect a set of known working RCA cables between your amp and source unit. If this causes the protection light to turn off, replace your current faulty RCA cables with new ones.
• Check the amp impedance limit. Another culprit is a set of speakers that do not match the amplifier’s recommended impedance load. Multiple loudspeakers connected to the same amp channel can cause the amp to protect. If the speakers are not connected correctly in a series, parallel, or series-parallel setup that keeps the impedance within the amplifier’s limits. Check each speaker’s connection to make sure it is making good contact and secure. Ensure you are not surpassing the amps recommended impedance load. Remember, the lower the total impedance, the more the speaker system requires of the amplifier. If your impedance is lower than the amplifier’s capabilities, you’ll need to reduce the impedance load by removing speakers from that channel’s chain. For help with properly wiring your speakers, please see our Woofer WiringWizard.
• Check for thermal issues. When an amplifier gets too hot, a thermal protection circuit may cause the amplifier to shut off. If your amp is experiencing thermal issues, it will often work again after it cools down. However, continued use and overheating may cause permanent amp failure. Make sure your car amp has ample ventilation.
• Check for an inadequate power supply. This can be caused by several issues. Improper cable size can result in inadequate voltage and/or current to the amplifier. Be sure to use the proper gauge as recommended for your amp. Poor connections can also cause a voltage drop. Inadequate termination of power and ground cables can cause high resistive connections. If any termination at the amplifier, fuse, or distribution block is hot, this indicates a highly resistive connection. Remove the cable and re-secure it by properly tightening the set screw. Also, a poorly connected ground wire can also trigger a problem. Ensure a good ground connection by sanding paint away at the point you are making the connection. Do not use the seat bolt as a grounding point. Check for consistent voltage from your battery and that the vehicle’s alternator is working.
• Check for improper gain control settings. The gain adjustment is a level control that matches the amplifier’s input to the source unit’s output voltage. Essentially, by dialing-in the gain control, you are telling the amp how much signal you’re putting into it so the amplifier will reproduce the signal accurately. If you have the gain set too high, the amp will make full power right away, and you’ll have problems with distortion and “clipping.” Refer to our Knowledge Base on properly setting gains.
• Note when the amplifier goes into protection. If the amplifier goes into protection when the system is first turned on, it’s likely a wiring issue. Disconnect all signal inputs and speaker wires from the amplifier, If the protection LED stays on, it implies a faulty amp. Does it protect after extended play sessions? Most likely, you are experiencing a thermal issue. If it goes into protect when driving on a rough road, then loose connections or faulty wiring are likely the culprits.

How do you know if your amp is blown?

If you have checked everything above (speakers, wiring, power source, grounding, etc.) and the amp still does not work, or the protection indicator light remains on with nothing plugged into the amplifier, you might have a blown amp. Other signs of a blown amp include a strange popping noise emitting from the speakers, a burning smell, or smoke. In this case, disconnect the amp and remove it from the power source to get the amplifier serviced. Check our Knowledge Base on how to get your amplifier repaired.

Can a car amplifier drain your battery?

When operating your audio system with the car running, the alternator provides the current needed to keep your amplifier running. If you run it with your car’s engine off, the battery provides the current needed for your amplifier. However, since the alternator is not keeping the car battery charged it will lead to a drained car battery, possibly to the point where your vehicle may not start. Ideally, you want your car engine running when the audio system is on to avoid this problem. If you plan on playing music for extended periods when parked with the engine off, you should consider getting a deep-cycle battery or a second battery to serve as the power supply.

If your battery is draining while the stereo is not on, you should check the remote wiring from the source unit to the amplifier. Typically, this is a blue wire off the source unit. This wire needs to be connected to the amplifier’s remote (REM) connector that turns the amp off when the stereo unit is turned off.

Finally, while there are complex equations to determine your alternator’s capacity and reserve for audio, here is a more straightforward way to get started. A 35-amp alternator (often in compact cars) can handle up to 300 watts of power. An alternator capable of producing 65 amperes is typically adequate for up to 500-watt systems, while a large SUV with a 145-amp alternator should be adequate for a 1,200-watt system. These are rough estimates and rely heavily on accessories used while operating the audio system.

Why does my amp get hot so fast?

Car amplifiers produce power. This creates heat, sometimes a lot of heat. Each amplifier is designed with a means of dispersing this heat through the use of heatsinks. Some amplifiers use fans to assist with dispersing the heat generated. The best amplifiers, like Rockford Fosgate amps, disperse heat efficiently. Cheap amplifiers are typically ineffective with heat transfer, and this inefficiency can cause the amplifier to overheat.

In addition to purchasing a premium amplifier, ventilation, proper cabling, wiring, and power matching is vital when installing an amp in your vehicle. Keep these in consideration when mounting your amplifier:

• Remember that heat rises, so mounting your amplifier where heat-sink fins are vertical, causes a “chimney effect.” Never mount an amplifier upside down, or you will counter-act the designed heat flow dispersion. Leave as much space above the amp as possible.
• Do not place your amplifier under carpet or cover it.
• In rare cases, you might need a fan to blow away the heat.
• Make sure the amp is properly matched to the power needs of the speaker(s) it is driving. Check the amp voltage while playing. If it dips below 12 volts, you don’t have enough power, which forces the amp to work harder.
• Check the ground wire with your ohm meter. Verify it has a clean connection to a sanded surface of your vehicle and make sure it is securely fastened. There should be minimal resistance between the vehicle chassis and the ground cable.

What if my lights or other car electronics dim or flicker when I play music loudly?

Your car, truck, or SUV’s battery or alternator may not be capable of handling the additional power that’s being pulled by your amplifier(s) when your audio system operates at higher volumes. A common issue is dimming headlights during the nighttime. This is an obvious indicator your audio system is pulling too much current for the alternator to handle. If you experience this:

• Check your battery. A local auto store can perform a battery load test. Aging batteries lose their ability to store and provide current.
• Consider upgrading the alternator. Compare the power demands of your stereo and audio components to that output capacity of your alternator. Many car audio competitors upgrade their alternator.
• Get a capacitor. Capacitors store power help supplement the power demand spikes on your battery and alternator. Capacitors work well with Rockford Fosgate amplifiers since they do not use regulated power supplies. The recommended capacity is 1 Farad per 1,000 watts.

Can my car amplifier be repaired?

Take your amplifier to an Authorized Rockford Fosgate Dealer for diagnosis and repair. The trained professionals ensure your amp is both safe and functioning at optimal performance. They can tell you whether an amp is repairable or if it is wiser to buy a replacement amplifier for your car audio system. You can also check our Knowledge Base on how to get your amplifier repaired.

Does my car amplifier have a warranty?

While we can’t answer for other brands, Rockford Fosgate amplifiers are protected by a factory warranty. We want you to get the performance and reliability Rockford Fosgate amps are famous for.

We also offer an extended warranty for your vehicle’s amplifier. Using poor-quality under-spec wiring is a guaranteed way to get less than you paid for. Getting your system wired with the correct cables and wire will make a difference. We are so certain of this that we provide an additional (1) year warranty on select amplifiers when used with the matching amp installation kit. Check our Knowledge Base on amplifier warranties and extended warranty programs.

Rockford Fosgate Offers Premium Car Amplifiers

Buying a Rockford Fosgate amplifier will eliminate or significantly reduce problems. Our amplifiers are designed for sound quality, performance and reliability. Incredible efficiency ensures your Rockford Fosgate amplifier produces clean, articulate sound instead of just heat. Chose from our three lines of mobile amplifiers – Prime, Punch and Power – to meet your budget requirements and performance needs. When you pair a Rockford Fosgate amp with Rockford Fosgate speakers, you’ll have a car audio system that will turn heads while providing you the ultimate listening experience.