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P0812 is a diagnostic trouble code (DTC) for "Reverse Input Circuit". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $154.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $50.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
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The P0812 trouble code identifies a reverse input circuit problem.
This code is triggered when the PCM (Powertrain Control Module) has discovered a problem with the reverse input circuit. When the driver puts their vehicle in reverse, they do so by using the shifter, which is then energized. The PCM monitors this process to ensure the voltage from this switch falls within an acceptable range predetermined by the manufacturer.
When the PCM detects an irregular amount of voltage or that there was resistance from the reverse input circuit, the P0812 code will be stored.
There are three main causes that usually result in a P0812 code being stored:
This code will almost always coincide with the Check Engine light coming on. However, some models are designed to only activate this light once the problem has been detected at least two or three times. In some cases, the backup lamps may also quit working.
In order to diagnose the problem behind this code, the mechanic will need to:
As we mentioned above, one of the symptoms of this code is that the backup lamp may quit working. This is usually because of a short in the wiring, though it could also have to do with a faulty reverse input switch or bad connectors. However, a hasty mechanic may immediately assume that the problem has to do with the lamp bulbs.
There is nothing inherently dangerous about the P0812 code. That being said, if it results in the backup lamps burning out, the driver will need to get around with them. That can be dangerous as other drivers won’t have forewarning when the automobile is backing up. Getting caught with this problem could earn the owner a ticket, too, one that will probably cost a lot more than just going in for repairs.
Repairing a malfunctioning reverse input circuit will usually involve some combination of the following:
When carrying out repairs, the manufacturer’s diagram for the specific make and model should be used to make sense of the circuits that need to be tested. If the vehicle has an automatic transmission, this switch is usually part of a neutral safety switch or manual lever position sensor. With manual transmissions, the switch may be threaded by the gear shifter to the transmission housing.
YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.