P0513 on 2015-2019 GMC Sierra 3500: Incorrect Immobilizer Key Causes and Fixes

What's Unique About the 2015-2019 Gmc SIERRA 3500

While P0513 universally points to a key or security issue, on the K2XX platform (which includes the 2015-2019 Sierra 3500), the problem is very frequently an electrical fault rather than a defective key. These trucks are known for water intrusion into the driver's side footwell, which causes corrosion in the wiring harness that runs under the sill plate. GM has issued specific Technical Service Bulletins (like PIT5391F) that identify an open or high resistance in circuit 5199 within this harness as a primary cause for P0513, making a physical wire inspection crucial before replacing any expensive components.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Engine cranks but will not start
• Engine starts and immediately stalls
• Security or anti-theft light is illuminated or flashing on the dashboard
• Check Engine Light is on
• Service Engine Soon (SES) lamp may not illuminate when the ignition is in the 'Run' position, as noted in TSB #PIT5391E.
• Multiple other warning lights may appear, such as 'Service 4WD', due to the underlying electrical fault.

Most Likely Causes

1. Damaged or Corroded Wiring at Driver's Sill Plate (Circuit 5199) 🔴 High Probability This is a well-documented issue on GM's K2XX truck platform. Water leaks into the cabin and pools in the wiring channel under the driver's door sill trim, corroding critical wires. TSB #PIT5391F directly links P0513 to an open or high resistance in circuit 5199 (Ignition 1 voltage) in this harness.
   How to confirm: Remove the driver's side front and/or rear sill plates and peel back the carpet to physically inspect the large wiring harness. Carefully unwrap the factory tape and look for signs of moisture, green or white corrosion (verdigris), and broken or chafed wires, paying special attention to small gauge wires.
   Typical fix: Cut out the damaged sections of wire, and splice in new wire using high-quality, sealed (heat-shrink) butt connectors to prevent future moisture intrusion. Soldering the connection before heat-shrinking provides an even more robust repair. Repairing the source of the water leak (e.g., third brake light seal, sunroof drains) is also recommended.
   Est. part cost: $10-$30
2. Poor Body Control Module (BCM) Ground (G218) 🟡 Medium Probability → Shop Body Control Module TSB #PIT5405C identifies a poor ground at location G218 as a cause for P0513 and a host of other communication codes. This is often caused by an insulation mat or other material being trapped under the ground terminal during factory assembly, preventing a solid connection.
   How to confirm: Locate ground G218 behind the driver's side kick panel, near the emergency brake pedal assembly. Remove the 10mm nut and inspect the connection. Check if the dash insulator foam is caught under the eyelet terminal.
   Typical fix: Remove the nut, pull the ground terminal away, and trim back any interfering insulation material. Clean the terminal, the vehicle body stud, and the nut with a wire brush or sandpaper to ensure a clean metal-to-metal contact, then securely retighten.
   Est. part cost: $0-$5
3. Weak or Failing Vehicle Battery 🟡 Medium Probability → Shop Vehicle Battery Modern trucks have high electrical demands. Low system voltage during cranking can cause communication errors between modules, triggering a P0513 code. TSB #21-NA-277 notes that this code can appear after a low voltage event, jump start, or battery replacement, sometimes requiring a dealer software procedure if a simple battery replacement doesn't clear it.
   How to confirm: Test the battery with a multimeter or a professional battery tester. A healthy, fully charged battery should read approximately 12.6 volts with the engine off and above 13.7V with the engine running. Check for loose or corroded terminals.
   Typical fix: Clean the battery terminals and cable ends. Ensure clamps are tight. Charge or replace the vehicle's 12V battery if it fails a load test.
   Est. part cost: $150-$350
4. Faulty Immobilizer Key ⚪ Low Probability → Shop Door Lock Key While this is a common cause on many vehicles, it is less likely on this specific truck than the known wiring and ground issues. The transponder chip in the key can be damaged by being dropped or from water exposure.
   How to confirm: Try starting the vehicle with a spare key. If the spare key works consistently, the original key is faulty. This is the easiest and quickest diagnostic step.
   Typical fix: Replace the faulty key. This requires purchasing a new key and having it programmed to the vehicle by a dealership or a qualified automotive locksmith.
   Est. part cost: $75-$250

Rare But Worth Checking

• BCM Software Corruption: As noted in TSB #21-NA-277, a low voltage event can sometimes corrupt the BCM's memory, causing a persistent P0513 even after the battery issue is resolved. This often requires a dealer to perform a specific software recovery or update procedure and the TSB explicitly states NOT to perform an immobilizer learn or replace modules until contacting GM technical assistance.
• Faulty Ignition Switch or Antenna Ring: → Shop Ignition Switch The antenna ring (transponder exciter) around the ignition cylinder reads the key's transponder chip. A failure in the ring or the switch itself can prevent the signal from being read, though this is far less common than the wiring and ground issues on this platform.
• Backed-out Terminals at Fuse Block: TSB #PIT5391A mentions that terminals can back out of their connectors at the Underhood Fuse Block (X50A) or the Left I/P Fuse Block (X51L), causing a loss of Ignition 1 voltage. Specifically, it calls out checking connector X4, pin M5 for circuit 5199.

Diagnosis Steps

1. Scan for all DTCs in all modules. Note if P262B or any U-codes are present, as this points towards known TSB issues.
2. Try starting the vehicle with a known-good spare key. If it starts, the primary key is likely the problem.
3. Test the vehicle's 12V battery. Ensure it has at least 12.6 volts with the engine off and that terminals are clean and tight. A low voltage event can trigger this code.
4. Following TSB #PIT5391F, remove the driver's side door sill plate and pull back the carpet to thoroughly inspect the wiring harness for any signs of corrosion, damage, or previous improper repairs. Focus on circuit 5199.
5. Inspect and clean the BCM ground connection G218. Locate it behind the driver's side kick panel, trim any interfering insulation mat, clean the contacts, and retighten the 10mm nut, as per TSB #PIT5405C.
6. If wiring and grounds are good, inspect fuse block connectors for backed-out terminals, particularly at the Underhood Fuse Block (X50A), connector X4, pin M5.
7. If all else fails, further diagnosis of the keyless entry antenna, ignition switch, and BCM may be required, which might necessitate professional-level scan tools.

Parts You'll Likely Need

• Wiring Repair Supplies — This is the most common fix, required to repair corroded wires (especially circuit 5199) under the driver's sill plate.
  Trusted brands: 3M, Dorman
  OEM price range: $10-$30
  Aftermarket price range: $10-$30
• Immobilizer Key (Uncoded) (OEM #13523213 (supersedes 13590048, 13517399, 13515243, 13510388)) — Needed if the transponder chip in the original key has failed, which can be confirmed by testing a spare key. Must be programmed by a dealer or locksmith.
  Trusted brands: ACDelco (Genuine GM)
  OEM price range: $50-$90
  Aftermarket price range: $30-$70
• Vehicle Battery — A weak battery can cause communication glitches that trigger this code. TSB #21-NA-277 specifically addresses this scenario.
  Trusted brands: ACDelco, DieHard, Interstate
  OEM price range: $200-$350
  Aftermarket price range: $150-$250

Related Codes That Often Appear With This One

• P262B — TSB #PIT5391E explicitly links P0513 and P262B to the same wiring issue in the driver's sill plate harness. Seeing them together is a strong indicator of this specific problem.
• U0073, U0140, U0100, U0121 and other U-codes — A flood of communication (U-prefix) codes alongside P0513 strongly suggests a systemic electrical problem, such as the poor BCM ground at G218, as documented in TSB #PIT5405C.

Technical Service Bulletins (TSBs) & Recalls

• PIT5391E: Addresses a no-start or start-stall condition with DTC P0513 and/or P262B, pointing to damaged or corroded wiring in the driver's sill plate, specifically circuit 5199.
• PIT5405C: Details numerous electrical issues (including P0513, stalls, and blank instrument clusters) caused by a poor BCM ground at G218 or other power/ground issues.
• 21-NA-277: Describes a condition where P0513 sets after a low voltage event and advises against module replacement, suggesting a potential software glitch that requires technical assistance.

Platform-Specific Known Issues

• TSB #PIT5391E (and later revisions like F) directly links P0513 to damaged or corroded wiring in the driver's sill plate area, a common point of failure due to water intrusion on the K2XX platform.
• TSB #PIT5405C identifies a poor ground at G218, often impeded by an insulation mat from the factory, as a root cause for P0513 and numerous other electrical communication faults.

Mechanic-Grade Diagnostic Values

• System Voltage (Engine Off) — expected: ~12.6 Volts. Failure: Voltage below 12.4V indicates a discharged battery that can cause module communication errors.
• System Voltage (Engine Running) — expected: 13.7 - 14.7 Volts. Failure: Voltage outside this range indicates a charging system problem that can lead to low voltage and communication faults.
• Voltage on Circuit 5199 (Ignition 1 Voltage) — expected: Battery Voltage with key in 'Run' position. Failure: Zero volts or significantly lower voltage than battery voltage indicates an open or high resistance in the circuit, as described in TSB PIT5391.
• Battery Terminal Torque — expected: 62 lb-in (7 Nm). Failure: Loose terminals can cause intermittent low voltage conditions, triggering P0513.

Hidden / Shadow Codes Worth Checking

• B389A 00: Indicates a BCM memory corruption issue, often after a low voltage event. Its presence strongly suggests the need for a BCM software recovery procedure rather than parts replacement. (see via Dealer-level scan tool like GM GDS2. TSB #21-NA-277 notes that a battery disconnect/reconnect for 30 seconds may be needed to see if the code sets.)
• B3978 00, B3979 00, B3980 00, B3981 00: These are Environment ID DTCs. If three or more are present and current in the BCM, it is a key indicator for the software corruption condition described in related TSBs. (see via Dealer-level scan tool like GM GDS2 that can read current and history body codes.)

Scan Tool Commands That Help

• GM GDS2 / SPS2 (Service Programming System): BCM Recovery / Programming per TSB — This is the primary, dealer-level fix when P0513 is set after a low-voltage event (e.g., battery replacement, jump start). TSBs #21-NA-277 and #23-NA-165 explicitly state to perform this software restoration *before* replacing any modules.
• GM GDS2 / SPS2: Immobilizer Learn — This function is used to program new keys to the vehicle. For the low-voltage software glitch, TSBs warn *not* to perform this procedure until after the BCM recovery has been successfully attempted, as it will not solve the underlying issue on its own.

Wiring & Ground Locations

• G218 — Behind the driver's side kick panel, near the A-pillar and emergency brake pedal assembly. It is a ground stud on the body.. This is a primary ground for the Body Control Module (BCM). TSB #PIT5405C identifies a poor connection here, often due to the dash insulator mat being trapped under the terminal, as a cause for P0513 and a wide range of other communication DTCs.
• Circuit 5199 — A purple wire running within the main wiring harness located under the driver's side door sill plate.. This circuit provides Ignition 1 Voltage. TSB #PIT5391 directly attributes P0513 and no-start conditions to this specific wire becoming corroded or broken due to water intrusion in the sill plate channel.
• Underhood Fuse Block (X50A), Connector X4, Pin M5 — The main fuse block in the engine compartment. X4 is one of the large multi-pin connectors on the underside of the block.. This is the source pin for Circuit 5199. TSBs note that a backed-out or corroded terminal at this specific pin can cause the same loss of Ignition 1 voltage as a damaged wire downstream, and should be checked if the sill plate wiring appears intact.

Real Owner Repair Stories

• Composite of owner experiences on forums like GM-Trucks.com and guidance from GM TSB #PIT5391. (2015-2019 GMC Sierra / Chevy Silverado (K2XX Platform)) — Intermittent no-start or start-and-stall. Security light on, Check Engine Light on with code P0513 and sometimes P262B. Often, the 'Service Engine Soon' light would fail to illuminate at all during the failure event.
  ❌ Tried (didn't work) Replacing the key fob battery., Trying the spare key., Replacing the vehicle battery (though sometimes this temporarily resolved the issue due to improved voltage)., Clearing the codes, only for them to return on the next failed start attempt.
  ✅ What actually fixed it The definitive fix was pulling up the driver's side door sill plate, unwrapping the large wiring harness, and finding a corroded (often green and powdery) or broken small-gauge wire (Circuit 5199). The damaged section of wire was cut out and a new piece was spliced in using heat-shrink butt connectors to seal the repair from future moisture.

OEM Part Supersession History

• 84504225, 84796410 → 84874317 — Standard part revision for the Front Sill Plate.
  Heads up: This is relevant for owners who may break the sill plate clips or damage the plate while accessing the wiring harness underneath for the common P0513 repair.

Model Year Variations Within This Range

• 2015-2019: The core electrical architecture and the specific failure points for code P0513 (sill plate wiring, G218 ground) are consistent across the entire 2015-2019 K2XX generation. A mid-cycle refresh occurred in 2016, but it did not alter the location or nature of these common faults.