Fault code P0817 is called “Starter Disable Circuit Malfunction” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P0817
OBD-II fault code P0817 is a generic fault code that is defined as a “starter trip circuit fault”. It is set when the Powertrain Control Module (PCM) detects a fault in the starter disconnect switch circuit.
The starter disconnect switch is a single-circuit switch that interrupts the voltage between the ignition switch and the starter solenoid. The Transmission Control Module (TCM) monitors the voltage in the starter disconnect circuit when the ignition is on.
To start the starter, an input voltage is applied to the relay when the ignition key is turned to the “Start” position. When the input circuit closes, the solenoid is activated and the battery voltage is transmitted through contacts directly to the starter solenoid. This actuates the electric motor to crank the engine.
When the ignition key is released, the input voltage is interrupted, de-energizing the solenoid. The spring-loaded contacts then return to the open position.
If a problem is detected while monitoring the starter disconnect circuit, code P0817 will be stored and the malfunction indicator lamp (MIL) may illuminate. Depending on the perceived severity of the fault, it may take several failure cycles for the MIL to illuminate.
Symptoms of vehicle malfunctions
The main signal that an error P0817 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- The “Check engine” control lamp on the control panel will light up (the code will be recorded in the memory as a fault).
- The engine will not start.
- The engine starts when a gear is engaged.
- There is a sound from the starter, without the engine cranking.
- There may be no symptoms other than a stored fault code.
The severity of the stored P0817 code can vary greatly, it depends on the specific symptoms. It may just be a glowing malfunction light, or the car will stop starting altogether.
Factors that can cause this error code
The error code P0817 can mean that one or more of the following problems have occurred:
- The starter disconnect switch is defective.
- Open or short circuit in wiring harness.
- Loose or damaged connectors.
- Poor grounding is a common cause.
- Low charge level or fully discharged battery.
- Blown fuses.
- Defective starter.
- Sometimes the cause is a faulty PCM module or programming error.
How to fix or reset OBD-2 code P0817
Some suggested steps for troubleshooting and fix the error code P0817:
- Read all stored data and error codes with an OBD-II scan tool. To find out when and under what circumstances error P0817 appeared.
- Clear the error codes from the computer memory and test drive the vehicle to see if the fault appears again.
- If the error code appears again, visually inspect the electrical wires and connectors.
- Visually inspect and test the starter disconnect switch and the starter itself.
- If necessary, repair or replace the starter and any defective wires.
- Check the fuses and the battery.
- If there are no defects, check the PCM itself and its software part.
Diagnose and repair of problems
To troubleshoot the P0817 fault, all stored data and error codes must be read with an OBD-II scan tool. This information may be useful if an intermittent fault is later diagnosed.
If there are no additional codes, the first thing to do is to check the battery to determine its state of charge and overall performance. If the battery is discharged or damaged, recharge or replace it.
Checking the wiring
After checking the battery, visually inspect all wiring associated with the starter. If necessary, repair or replace to ensure effective load transfer.
If no visible signs of shorts or other damage are found, use a voltmeter to check resistance and ground. Replace if necessary to ensure that all electrical values are within the limits specified by the manufacturer.
Also locate any fuses that are in any way connected to the starting system. After checking, replace any damaged or suspect fuses.
Testing the starter
If all the wiring is checked, you need to test the starter disconnect switch and the starter itself with a multimeter. In most cases, it is the defective starter or its components that cause error P0817.
If the defect in the starter is confirmed, replace it with a new or rebuilt starter, as this is almost always more cost-effective than repairing it. However, make sure that the unit being replaced is identical to the original in all respects, including mounting brackets and features.
After replacement, start the engine and monitor the indicator light on the dashboard to make sure the starter is working properly. The warning light should go out within a few seconds.
You can also measure the system voltage and it should be between 14.2 and 14.8 volts. Allow the vehicle to run at least one full drive cycle before rescanning the system. Most likely there will be no P0817 error, but sometimes additional clearing with a special scanner is necessary.
On which vehicles does this problem occur most frequently
Fault code P0817 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- Audi
- BMW
- Dodge (RAM)
- Ford (Mondeo, Transit)
- Land Rover (Freelander)
- Mazda (CX-9)
- Mercedes-Benz
- Subaru (Legacy, Outback, Tribeca)
- Volkswagen
Fault code P0817 can sometimes be found with other errors. The most common are the following: P0480, P081A, P081B.
