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2021 Ram 1500 Longhorn - 'Key Fob Not Detected' Intermittently

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Ashley M. · rep 0 · May 22, 3:34 AM · 1 replies · solved · Question

Vehicle: 2021 Ram 1500 Longhorn

Hey everyone,

I'm having a really annoying issue with my 2021 Ram 1500 Longhorn. Lately, I've been getting the 'Key Fob Not Detected' message on the dash, even when the key fob is right there in the cabin. This prevents me from starting the truck with the push-button start. Sometimes, I have to hold the fob right up to the start button for it to work, and other times it just won't recognize it at all.

I've already replaced the battery in the key fob, thinking that was the problem, but it didn't help. It's happening more frequently now, and I'm worried about getting stranded. Could this be an issue with the truck's receiver or a module?

Has anyone else with a 2021+ Ram experienced this? Any ideas on what might be causing it or how to fix it?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:34 AM

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ClearTheCode admin answer:

Intermittent 'Key Fob Not Detected' messages on your 2021 Ram 1500 can be a frustrating and potentially stranding issue. Here's a breakdown of potential causes and steps to take:

  1. Test Both Key Fobs: If you have a second key fob, try using it exclusively for a few days. If the problem disappears, the issue is likely with your primary fob, even if you've replaced its battery. The fob itself might be faulty.
  2. Check for RF Interference: Other electronic devices in the vehicle (e.g., dash cams, phone chargers, radar detectors) or even strong external radio frequency (RF) signals can sometimes interfere with the key fob's communication. Try removing or turning off such devices temporarily.
  3. Inspect the RKE (Remote Keyless Entry) Antenna/Module: The truck has an antenna system that receives the key fob's signal. A faulty antenna or the associated RKE module (sometimes integrated with the BCM or WIN module) could be the culprit. These components can develop intermittent faults.
  4. OBD-II Scan: A diagnostic scan can be very helpful. Look for codes related to the RKE system or the Ignition Node Module (WIN/WCM). Relevant codes might include:
    • B1A28: Key Fob Battery Low (even if you replaced it, the truck might not be reading it correctly).
    • B1A29: Key Fob Not Programmed (unlikely if it sometimes works, but worth checking).
    • B1A30: Ignition Node Module Internal Fault.
    • U0140: Lost Communication With Body Control Module (if the RKE module communicates through it).

Common Causes:

  • Weak or faulty key fob (even with a new battery).
  • RF interference.
  • Faulty RKE antenna or receiver module in the truck.
  • Wiring issues to the RKE module.

When to See a Shop: If testing with a second fob, checking for interference, and replacing the fob battery doesn't resolve the issue, it's best to take your Ram to a dealership. They have the specialized diagnostic tools to test the RKE system, check for module faults, and reprogram key fobs or replace faulty modules (like the WIN/WCM or RKE receiver) if necessary. This is a critical safety and security system, so professional diagnosis is recommended.

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