Faulty ignition switch (both sources; RepairPal's listed common repair is replacing it). Faulty starter relay (both sources). Open or shorted wiring in the starter request circuit (both sources). Blown fuses or burnt fusible links (OBD-Codes.com only). PCM failure or PCM programming error (both sources).

Replace blown fuses or burnt fusible links, and find out why they blew (OBD-Codes.com). Replace a faulty starter relay (both sources). Repair open or shorted wiring in the starter request circuit (both sources). Replace the ignition switch if it isn't sending the start signal (both sources; RepairPal lists this as the common repair). Repair, replace or reprogram the PCM (both sources; only after other causes are ruled out).

P0512🔧 Starting systemDrive with caution, fix soon

P0512: Starter Request Circuit (Meaning, Causes, Fixes)

Q: What does P0512 mean?

P0512 means the engine computer has detected a problem in the starter request circuit, the signal that tells the starter to crank when you turn the key. Common causes are a bad ignition switch, a faulty starter relay, a blown fuse or a wiring fault. When you turn the key to start, the ignition switch sends a starter request signal that energizes the starter solenoid, or a starter relay on many vehicles, so the starter motor cranks the engine. OBD-Codes.com explains that on vehicles that set P0512, the powertrain control module (PCM) should also receive that starter request signal, and the code is stored when the PCM detects a malfunction in the circuit, usually because it didn't receive the signal. On vehicles with a starter relay, the ignition switch typically signals the relay, and the PCM provides the relay's ground. OBD-Codes.com calls it a generic code for 1996-and-newer vehicles, mentions Dodge, Chrysler, Hyundai, Jeep and Mazda, and notes that it's rarely seen on vehicles without a starter relay. Some vehicles need several failed ignition cycles before the check engine light comes on. The sources describe the circuit a little differently: RepairPal says the starter relay receives a signal from the PCM telling the starter to crank, and the PCM sets P0512 when it detects an incorrect signal to the starter relay or the starter. OBD-Codes.com describes the request signal as starting at the ignition switch and being reported to the PCM.

Q: Can I keep driving with P0512?

Drive with caution, fix soon. The two sources disagree. OBD-Codes.com says that if the engine cranks normally, P0512 can be addressed at your convenience, but it needs attention with some urgency if the engine won't start. RepairPal rates P0512 Urgent, its highest level, meaning immediate action is needed. Because the main risk is the car failing to start, get it checked soon, before it leaves you stranded.

Reviewed 2026-10-25 · Based on 2 cited source(s)

What P0512 means

When you turn the key to start, the ignition switch sends a starter request signal that energizes the starter solenoid, or a starter relay on many vehicles, so the starter motor cranks the engine. OBD-Codes.com explains that on vehicles that set P0512, the powertrain control module (PCM) should also receive that starter request signal, and the code is stored when the PCM detects a malfunction in the circuit, usually because it didn't receive the signal. On vehicles with a starter relay, the ignition switch typically signals the relay, and the PCM provides the relay's ground. OBD-Codes.com calls it a generic code for 1996-and-newer vehicles, mentions Dodge, Chrysler, Hyundai, Jeep and Mazda, and notes that it's rarely seen on vehicles without a starter relay. Some vehicles need several failed ignition cycles before the check engine light comes on. The sources describe the circuit a little differently: RepairPal says the starter relay receives a signal from the PCM telling the starter to crank, and the PCM sets P0512 when it detects an incorrect signal to the starter relay or the starter. OBD-Codes.com describes the request signal as starting at the ignition switch and being reported to the PCM.

Severity: can I keep driving?

Drive with caution, fix soon

The two sources disagree. OBD-Codes.com says that if the engine cranks normally, P0512 can be addressed at your convenience, but it needs attention with some urgency if the engine won't start. RepairPal rates P0512 Urgent, its highest level, meaning immediate action is needed. Because the main risk is the car failing to start, get it checked soon, before it leaves you stranded.

Common symptoms

Engine may fail to start (both sources)
Delayed starter engagement, needing more than one turn of the key (OBD-Codes.com)
Other codes for PCM power or ignition circuit failures may be stored with it (OBD-Codes.com)
Often no symptoms at all besides the check engine light (OBD-Codes.com)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Faulty ignition switch (both sources; RepairPal's listed common repair is replacing it)
Faulty starter relay (both sources)
Open or shorted wiring in the starter request circuit (both sources)
Blown fuses or burnt fusible links (OBD-Codes.com only)
PCM failure or PCM programming error (both sources)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Check for technical service bulletins (TSBs) for your vehicle first, as OBD-Codes.com recommends; your problem may be a known issue with a known fix.
Inspect the wiring and connectors in the starting circuit for damage, loose connections and corrosion.
Check the starter system fuses and fusible links. OBD-Codes.com says to check fuses while the starter is engaged, because a fuse can look fine until the circuit is loaded.
Find out from a repair manual whether your vehicle has a starter relay. If it does, swap it with an identical relay with a matching part number from another circuit; if the problem goes away, put the relays back and replace the starter relay with a new one.
After any repair, clear the code and drive normally until the PCM's readiness monitors run or the code returns, so you know the fix worked (OBD-Codes.com).

Typical fixes

Replace blown fuses or burnt fusible links, and find out why they blew (OBD-Codes.com)
Replace a faulty starter relay (both sources)
Repair open or shorted wiring in the starter request circuit (both sources)
Replace the ignition switch if it isn't sending the start signal (both sources; RepairPal lists this as the common repair)
Repair, replace or reprogram the PCM (both sources; only after other causes are ruled out)

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

Testing needs a wiring diagram, a scan tool and a digital volt-ohm meter. OBD-Codes.com describes checking the switched voltage to the starter relay, the start signal from the ignition switch and the ground signal from the PCM
The engine won't crank or start, or starts only after several tries
No voltage reaches the starter relay from the ignition switch, pointing to the ignition switch or its wiring
The PCM isn't providing a ground to the starter relay, which can mean a PCM fault or programming problem
The code returns after replacing the fuse and relay

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Is P0512 serious?

It depends on how the car starts. OBD-Codes.com says it can wait if the engine cranks normally but needs prompt attention if the engine won't start. RepairPal rates it Urgent. Since it can lead to a no-start, it's best to get it fixed soon.

Can a bad starter relay cause P0512?

Yes. Both OBD-Codes.com and RepairPal list a faulty starter relay as a cause. OBD-Codes.com suggests swapping it with an identical relay from another circuit as a simple test.

Does P0512 mean my starter motor is bad?

Not usually. Neither source lists the starter motor itself as a cause. The code points to the request circuit: the ignition switch, starter relay, fuses, wiring or the PCM.

Sources

Last reviewed 2026-10-25. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.