P0513 on 2018-2020 Ram 2500: Incorrect Immobilizer Key Causes and Fixes

What's Unique About the 2018-2020 Ram 2500

For these Ram trucks, the P0513 code is often tied to the sensitive communication between the key fob, the Radio Frequency Hub (RFH), and the PCM. A manufacturer Technical Service Bulletin (TSB S2208000073) specifically notes that this code can appear after a PCM is replaced or has its software updated if the key reprogramming procedure isn't performed correctly. This highlights the importance of proper programming during major electronic repairs. Furthermore, owners have reported intermittent issues that can sometimes be traced back to seemingly unrelated electrical problems like corroded battery cables, which can disrupt the security system's function. On the 2019+ models, the RF Hub is also a known failure point due to its location, where it can be susceptible to water damage from a leaking rear window or third brake light seal.

Diagnostic Flowchart

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

Generation note: The 2018 model year is the final year of the fourth-generation Ram 2500, while 2019-2020 models are the fifth generation. While the underlying cause (security key mismatch) is the same, the specific modules (e.g., RF Hub) and diagnostic procedures may differ slightly between generations. For example, the 2018 key fob uses a CR2032 battery, whereas the 2019+ fobs use a CR2450. The RF Hub on 2019+ models is also more commonly reported as a failure point due to water intrusion. However, the primary causes and symptoms are consistent across this year range.

Symptoms You May Notice

• Engine cranks but will not start.
• Engine starts and then immediately shuts off.
• A red security light is flashing or stays illuminated on the dashboard.
• Remote functions like lock/unlock may fail to work.
• Check Engine Light is on.
• Dashboard message like "Key Not Recognized".

Most Likely Causes

1. Weak or Dead Key Fob Battery 🔴 High Probability → Shop Vehicle Battery Key fobs have a limited battery life of 2-4 years, and a weak signal is a common point of failure for any vehicle with a modern immobilizer system.
   How to confirm: Try starting the vehicle with your spare key fob. If the spare key works, the issue is with the primary key. You can also try the emergency start procedure: for push-button start, press the start button with the nose of the key fob. This uses a short-range antenna that can sometimes overcome a weak battery. 🎬 Watch: How to start your Ram with a dead key fob. Replace the battery (CR2032 for 2018 models, CR2450 for 2019-2020 models) in the non-working fob.
   Typical fix: Replace the battery inside the key fob.
   Est. part cost: $1-$10
2. Faulty Key Fob 🟡 Medium Probability → Shop Keyless Entry Transmitter The internal transponder chip or electronics within the key fob can fail from being dropped, water damage, or age. Owners on forums have reported keys randomly losing their programming.
   How to confirm: If replacing the battery and trying the spare key doesn't work, the key fob itself may be the problem. A locksmith or dealer can test the transponder's signal.
   Typical fix: Replace the key fob and have it professionally programmed to the vehicle.
   Est. part cost: $150-$400
3. Improper PCM/Key Programming After Service 🟡 Medium Probability As noted in TSB #S2208000073, this code is a known issue if the PCM is replaced or reflashed without correctly performing the 'PCM Replaced Procedure' to sync the security information with the RF Hub. The PCM defaults and loses the security code, causing the handshake to fail.
   How to confirm: This issue will occur immediately following a PCM replacement or software update, resulting in a no-start condition with P0513 active.
   Typical fix: A dealer or qualified shop must use a tool like wiTECH to perform the 'PCM Replaced' or 'Proxy Configuration Alignment' routine to re-synchronize the modules.
   Est. part cost: $0 (if part of the original repair) or 1-2 hours of shop labor.
4. Faulty Radio Frequency Hub (RFH) or Antenna ⚪ Low Probability The RFH is the module that receives the key's signal. Like any electronic module, it can fail. On 2019+ models, it is known to be vulnerable to water intrusion from a leaking rear window or 3rd brake light. The antenna ring around the ignition or start button can also be damaged.
   How to confirm: This requires advanced diagnostics with a scan tool that can communicate directly with the RFH/WCM (Wireless Control Module) to check for internal fault codes or communication errors. A visual inspection for water damage around the RF Hub (located behind the rear seats on 2019+ models) is also recommended.
   Typical fix: Replace the faulty RF Hub and program it to the vehicle. Some aftermarket suppliers offer pre-programmed modules.
   Est. part cost: $100-$300

Rare But Worth Checking

• Wiring or Connection Issue: Corrosion on battery terminals or main power feeds to the fuse box can cause low voltage and intermittent electrical issues, including disrupting the security system. One owner on RamForum.com fixed a recurring P0513 by cleaning a corroded battery cable to the fuse panel. It's worth checking for clean, tight connections before replacing expensive modules.
• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) While less common than other causes, an internal failure of the PCM can corrupt the security data and cause a P0513 code. This is typically a last resort after all other components (keys, RFH, wiring) have been verified as good.
• Aftermarket Remote Starter or Alarm: Improperly installed aftermarket remote start or alarm systems can interfere with the factory immobilizer communication, leading to intermittent P0513 codes. If the vehicle has such a system, it should be inspected as a potential cause.

Diagnosis Steps

1. Check for a flashing red security light on the instrument cluster. This confirms an active anti-theft issue.
2. Try your spare key. If the vehicle starts, the problem is isolated to your primary key fob or its battery.
3. Replace the battery in the key fob that is not working. This is the most common and cheapest fix. Use a CR2032 for 2018 models and a CR2450 for 2019-2020 models.
4. If the key fob battery is weak or dead, attempt the emergency start procedure by pushing the start/stop button directly with the nose of the key fob.
5. If neither key works, scan the vehicle for codes in the PCM, BCM (Body Control Module), and RFH (Radio Frequency Hub). Note any other security-related codes like B1A28 or U0426.
6. If the issue occurred directly after a PCM replacement or flash, the vehicle must be taken to a dealer or equipped shop to perform the 'PCM Replaced Procedure' as outlined in TSB S2208000073.
7. Using an advanced scan tool, check the status of the immobilizer system and verify how many keys are programmed.
8. Inspect the main battery terminals and power feed cables to the fuse box for corrosion or looseness.
9. For 2019+ models, inspect the RF Hub module (located behind the rear seats) and its connectors for any signs of water intrusion or damage.
10. If all keys, wiring, and programming are good, the RF Hub is the next most likely component to have failed and may require replacement and programming.

Parts You'll Likely Need

• Key Fob Battery (OEM #CR2032 (2018), CR2450 (2019-2020)) — This is the most frequent cause of a weak or non-existent signal from the key to the vehicle's security system.
  Trusted brands: Energizer, Duracell, Panasonic
  OEM price range: $5-$15
  Aftermarket price range: $1-$10
• Key Fob / Transponder Key (OEM #e.g., Mopar 56046955AG (confirm with VIN)) — If the internal electronics of the key fail, it must be replaced and programmed to the truck.
  Trusted brands: Mopar (OEM)
  OEM price range: $200-$400

Related Codes That Often Appear With This One

• B1A28 — This code, 'ECM MISMATCH WITH SKIM,' can be stored in the RF Hub when the security information from the PCM doesn't match, directly relating to the P0513 condition.
• U0426 — This code indicates invalid data was received from the Vehicle Immobilizer Control Module. TSB S2208000073 specifically mentions U0426-62 (MiniKrypt Error Signal Compare Error) appearing alongside P0513 after a PCM flash.

Technical Service Bulletins (TSBs) & Recalls

• S2208000073: No Start, After Flash And Or PCM Replace, DTC P0513 Invalid Skim Key Setting. Details the procedure to re-sync security modules after PCM service.

Platform-Specific Known Issues

• TSB S2208000073: A no-start condition with DTC P0513 can occur after replacing or reflashing the PCM if the key security data is not properly synchronized between the PCM, BCM, and RF Hub. The fix requires performing the 'PCM Replaced Procedure' or 'Proxy Configuration Alignment' with a dealer scan tool.
• Forum Experience (RamForum.com): A user with a recurring, intermittent P0513 issue traced the problem to a corroded battery cable connection at the fuse panel. Cleaning the connection resolved the no-start and remote lock/unlock failure. This highlights the importance of checking basic electrical connections before assuming module failure.

Mechanic-Grade Diagnostic Values

• Parasitic Draw (after sleep) — expected: 30mA - 50mA. Failure: A consistent draw of 2 amps (2000mA) indicates a significant short or a module that is not going to sleep, which can disrupt the security system. A reading of 140mA is also considered high.

Hidden / Shadow Codes Worth Checking

• B2229: SKIM Immobilizer Key Mismatch. This code is often stored in the Body Control Module (BCM) or RF Hub and indicates a direct conflict between the key data and the vehicle's stored data. (see via Dealer-level scan tool like wiTECH or a high-end aftermarket scanner with manufacturer-specific capabilities.)

Scan Tool Commands That Help

• wiTECH: PCM Replaced Procedure / PCM/ECM/ESL replace — This is required after replacing or reflashing the PCM. It forces the PCM to learn the vehicle's security credentials from the BCM and RF Hub. Failure to perform this will cause a P0513.
• wiTECH: Proxy Configuration Alignment — This routine is used to verify that all modules on the vehicle's network are communicating correctly and have matching configurations. It should be run after replacing any major module, including the PCM or RF Hub, to ensure all security data is synchronized.
• wiTECH: Restore Vehicle Configuration — This function can be used to restore the vehicle's original configuration data to a new module, which is critical when replacing the RF Hub or BCM to ensure all keys and security features are correctly recognized.

Wiring & Ground Locations

• RF Hub Module — For 2019+ models, the RF Hub is located on the rear wall of the cab, behind the rear seats, below the rear window. For 2018 (4th Gen) models, it is also on the back wall of the cab behind the rear seat.. This is the central receiver for the key fob signal. Its location on 5th Gen trucks makes it highly susceptible to water damage from a leaking third brake light or rear window seal, a common cause of failure leading to P0513.
• RF Hub Fuse — In the under-hood fuse box (Power Distribution Center), fuse F52 (a 5-amp fuse) powers the Radio Frequency Module on 2018 models.. A blown fuse will completely disable the RF Hub, preventing it from reading the key and causing an immediate no-start with a P0513 code.
• Main Frame Ground — A primary ground wire from the negative battery terminal connects to the frame on the driver's side, just in front of the wheel.. A poor frame ground can cause widespread, intermittent electrical issues, including voltage fluctuations that can disrupt the sensitive communication between the PCM, BCM, and RF Hub.
• RF Hub C2 Connector — This is the main electrical connector plugging into the RF Hub module itself.. Technicians may need to test for power, ground, and communication signals at this connector. For example, Pin 2 (GY/LB wire) is for a passive entry antenna signal. Water intrusion often corrodes the pins in this connector.

Real Owner Repair Stories

• 5thGenRams Forum (2019+ Ram 1500 (Applies to 2500 as well)) — Truck won't start, P0513 code, key not detected.
  ❌ Tried (didn't work) Replacing key fob battery, Trying spare key
  ✅ What actually fixed it The root cause was a water leak from the third brake light seal, which dripped directly onto the RF Hub module located on the back wall of the cab, shorting it out. The fix required replacing the RF Hub module, programming it to the vehicle, and resealing the third brake light to prevent recurrence. One owner reported a dealer bill of around $1800 for this repair.
• MHH AUTO Forum (2018 Ram 1500 (post-accident repair)) — Engine doesn't crank, flashing red security light, P0513 active.
  ❌ Tried (didn't work) Confirming key is seen by the vehicle (no 'invalid key' message on dash).
  ✅ What actually fixed it The problem was a loss of synchronization between the modules after the accident/repair. The official solution is to use the wiTECH2 tool with a dealer online account to program a new PCM. The discussion implies that after a major electrical disruption or module replacement, simply having the right key is not enough; the security handshake between the PCM, BCM, and RF Hub must be re-established via dealer software.

OEM Part Supersession History

• 68444358AB → 68444358AC — Standard revision update by the manufacturer. May include minor internal component changes for reliability.
  Heads up: The parts are interchangeable, but the newest revision (AC) is recommended. Programming is always required upon replacement.
• 68441622AA → 68441622AB — Revision update for the RF Hub receiver.
  Heads up: Parts are generally cross-compatible but always confirm fitment with VIN. A new RF Hub, regardless of part number, cannot be a used part from another vehicle; it must be a new part programmed to the specific truck.

Model Year Variations Within This Range

• 2019-2020 (5th Gen): The RF Hub is located on the rear cab wall in a position highly vulnerable to water damage from leaks in the rear sliding window or the third brake light (CHMSL) seal. This is the most common cause of P0513 on these specific model years, whereas it is a less frequent cause on the 2018 model.
• 2018 (4th Gen) vs 2019-2020 (5th Gen): The key fob design and battery type are different. 2018 models use a CR2032 battery, while 2019+ models use a CR2450. While this doesn't change the code's meaning, it's a critical detail for the first diagnostic step of battery replacement.