Nissan Sentra Horn Relay Replacement Cost

Know what price you should pay to get your vehicle fixed.

The average cost for a Nissan Sentra horn relay replacement is between $64 and $75. Labor costs are estimated between $41 and $52 while parts are priced at $23. Estimate does not include taxes and fees.
Note about price: The cost of this service or repair can vary by location, your vehicle's make and model, and even your engine type. Related repairs may also be needed. Talk with a RepairPal Certified shop to learn which repairs might be right for you.

How does the Horn Relay work?

The horn relay powers the horn, which takes considerably higher amperage than can be safely passed through the horn switch, but must be powered when the horn switch is pressed. A relay is the perfect tool for the job, and has remained reliable for decades. When the horn switch is pressed, electrical power is sent from the horn switch to the relay. Inside the relay there is a large circuit and a small circuit. The small circuit is for a signal from the horn switch and causes the large circuit to close(connect) through electromagnetism. When the large circuit closes, power can now flow from the battery, through the closed circuit in the relay, and to the horn. To turn off the horn, the horn switch being released stops electric power to the small circuit, so the electromagnet in the relay no longer closes the circuit. That means that when the electromagnet in the relay looses power from the horn switch, the large circuit will open (disconnect). When the large circuit opens, the horn loses power and stops running.

What are the symptoms of a bad Horn Relay?

Horn relay failure will manifest itself in one of three ways. It may cease functioning when the horn switch is pressed, always function, possibly with the vehicle turned off, or only function occasionally. These failures all point to the horn relay at some point during diagnostics, and the way the problem is presented will generally predict the type of failure. A horn relay that is stuck on all the time will constantly power the horn, sometimes with the vehicle off, as mentioned. Also, a weak horn relay will result in intermittent operation of the horn, while a failed relay will prevent the horn from functioning at all.

Can I drive with a bad Horn Relay?

If the horn is not functioning properly, many states will not permit the vehicle to operate on public roads or pass safety inspections. Also, this will pase a safety risk since the horn may not work in an emergency, which may allow a preventable collision to occur. When the horn, or any other safety feature on a vehicle is not functioning to standard, it should be addressed right away.

How often do Horn Relays need replacement?

Relays fail all the time, in new and old vehicles of all makes and models. Relays are generally reliable, but most vehicles will have at least one relay failure through the course of its service life. No matter how well made and how well maintained a vehicle is, the slightest bit of corrosion and years of wear on contact surfaces will eventually break down a relay. Also, if the relays are quickly powered on and off, such as with a dying battery, the contacts can arch and erode quickly.

How are Horn Relays replaced?

Replacing a relay is only a matter of identifying the relay according to diagrams in the owner's manual, under the lid of the power distribution or fuse block, or in the service manual for the vehicle. Once testing of the relay is complete, the failed relay is thrown away only after ensuring the new relay is exactly identical in function and size, and the new relay is firmly pressed in, pulled out, and once again pressed into the power distribution or fuse block. This will ensure that complete contact is made between the relay and the terminals on the vehicle.

RepairPal Recommendations for Horn Relay issues

Never attempt to repair a relay. There is generally nothing serviceable in a relay, and erroneous reconstruction will only lead to humidity entering the relay, a relay that does not function properly, or even melting of the entire relay. Relays are inexpensive sealed units that should be replaced, not tampered with.

What to look out for when dealing with Horn Relay issues

If a relay is proven good, but still does not function, the terminals can be tested in the junction block with a test light or multimeter. A multimeter is prefered because of the accuracy of readings, but a test light will inform the technician if power is present or not. Also, the horn switch may provide a switched ground to the horn relay, or it may provide a switched hot (battery voltage). This should be known when testing the relay and the power distribution block. In the case of a switched ground, there will only be continuity between the battery negative cable and the relay when the horn switch is pressed.

Can I replace the Horn Relay myself?

Relay testing and replacement is simple, straightforward, and could be a fun project to share with a family member. The issues start to emerge when the relay is diagnosed as operable, but is not activated when the ignition switch is turned on. If testing of electrical circuits is understood, and a multimeter with long leads is present, this repair can be accomplished at home, but if the circuit is not understood and the relay is good, leave the job to a professional. This will likely prevent further damage or electric shock.