Faulty or misadjusted park/neutral position switch or transmission range sensor; Open circuit, chafed wiring or corroded terminals in the starter disable or start inhibit circuit; Poor connection at the starter relay, its socket or the related fuse; Gear selector linkage or cable out of adjustment, so the switch reads the wrong position; Faulty starter relay or starter disable relay; Internal fault in the powertrain control module or a related body control module driver.

P0817

Starter Disable Circuit/Open.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
8: AreaTransmission
17: FaultThe specific fault in that area

What it means

P0817 is the generic code for a fault in the starter disable circuit. The powertrain control module controls a circuit that stops the starter motor engaging when the transmission is in gear, or when other start conditions are not met. It has seen a circuit fault, such as an open circuit or a mismatch between the commanded and actual circuit state, so the code was set.

Symptoms

Engine will not crank when the key is turned or the start button pressed
Engine cranks in gear when it should not, depending on how the fault shows itself
Intermittent no-start that comes and goes with selector position or wiggling the lever
Starting only works with the selector in Neutral rather than Park, or vice versa
Check engine light on, sometimes with a transmission warning
Reverse lights or gear position display behaving oddly

Possible causes

Faulty or misadjusted park/neutral position switch or transmission range sensorlikely
Open circuit, chafed wiring or corroded terminals in the starter disable or start inhibit circuitlikely
Poor connection at the starter relay, its socket or the related fusepossible
Gear selector linkage or cable out of adjustment, so the switch reads the wrong positionpossible
Faulty starter relay or starter disable relaypossible
Internal fault in the powertrain control module or a related body control module driverrare

How to diagnose

Read all stored codes and freeze frame data, noting which gear position and conditions were present when the code set
Check the battery state of charge and terminal condition, as low voltage can cause false circuit faults
Inspect the starter disable circuit wiring, connectors and the range switch plug for damage, water ingress and corrosion
Check the relevant fuses and the starter or disable relay, swapping with a known good identical relay if the layout allows
With a scan tool, watch the live gear position or range switch data while moving the selector through every position and compare it with the actual lever position
Check the selector linkage or cable adjustment against the manufacturer's procedure for that model
Test the circuit for continuity, short to earth and short to supply using the wiring diagram for the specific vehicle
Check the powertrain control module output and power and earth supplies only after wiring and switches are proven good

How to fix

Replace or adjust the park/neutral position switch or transmission range sensor and set it to specification
Repair damaged wiring and clean or replace corroded or loose connector terminals
Replace a faulty starter or starter disable relay with the correct type
Adjust or repair the selector linkage or cable so the position signal matches the lever
Replace or repair the control module only if it is confirmed faulty, and carry out any programming the manufacturer requires

Can I keep driving?

Medium severity

If the car starts and runs normally it can be driven for a short time, but the fault may leave you unable to restart, so get it checked soon. If it is cranking in gear or failing to start intermittently, avoid relying on it, as an unexpected stall or no-start can be unsafe.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.