P0504 on Kia: How to Diagnose & Fix
Brake Switch "A"/"B" Correlation
2 Kia models · 2 documented issues · 2 critical
P0504 on Kia by model: symptoms, diagnosis and fix
Kia recall SC098 (NHTSA 13V-114) covers 2008-2011 Optima vehicles with a stop-lamp switch that may malfunction. Brake lamps may fail to illuminate, cruise control may not disengage, push-button start or brake-transmission shift interlock operation may be affected, and the ESC warning light may illuminate. This indexed page retains its existing 2008-2010 year scope.
Common Symptoms
- Brake lamps do not illuminate
- Cruise control does not disengage with brake pedal
- Shift interlock or push-button start operates intermittently
- ESC warning light illuminated
How to Fix
Check the VIN for open recall SC098/13V-114 and have the free dealer repair completed. Kia dealers replace the stop-lamp switch. Because recall applicability is VIN-specific and the campaign remedy is free, no retail switch is linked.
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Sources for this issue (1)
The Sedona IS named in the Hyundai-Kia-wide brake-light switch campaign. Stop lamp switches supplied by INFAC were damaged during supplier assembly, letting the plunger inside the threaded shaft stick. The consequences are broader than a dead brake light: cruise control may not cancel when the driver brakes, the brake-transmission shift interlock may refuse to release the shifter from Park, push-button start may work only intermittently, and the ESC malfunction lamp can illuminate. Kia's 2013 recall (NHTSA 13V-114), part of the roughly 1.7 million-vehicle Hyundai/Kia action, lists 2007 Sedona alongside 2007-2010 Rondo and Sportage, 2007-2011 Sorento, 2010-2011 Soul, and 2011 Optima. A separate earlier Sedona campaign, 06V-349, covered a damaged brake-light WIRING HARNESS — a different defect on the same circuit, so confirm which applies to a given VIN.
Common Symptoms
- Brake lights do not illuminate when the pedal is pressed
- Brake lights stay on with the pedal released
- Shifter will not come out of Park with the brake pressed
- Cruise control does not disengage on braking
- ESC/traction warning lamp illuminated
- Push-button start works only intermittently
How to Fix
Free replacement of the stop lamp switch under NHTSA 13V-114 for covered 2007 vans. Outside the recall population the switch is an inexpensive part behind the brake pedal and a common cause of the same symptom set on other Sedona years — replace it before chasing the shift interlock solenoid or the ESC module. Confirm brake lamp operation at the pedal, not just at the third brake light.
Sources for this issue (4)
- NHTSA Recall 13V-114 acknowledgement — Hyundai/Kia stop lamp switcharticle
- Hyundai/Kia Recall 1.7 Million Vehicles for Rollaway Risk, Brake-Light Problem — Edmundsarticle
- Kia and the Breaking Brake Switch That's Been Broken — Safety Research & Strategiesarticle
- NHTSA Recall 06V-349 — Kia Sedona damaged brake light wiring harnessarticle
P0504 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0504 mean on a Kia?
P0504 stands for "Brake Switch "A"/"B" Correlation." Most vehicles use two independent brake switch signals (a normally-open and a normally-closed circuit, switch A and switch B). The PCM compares them and expects them to change state together when the brake pedal is pressed. P0504 sets when the two signals disagree (do not correlate), indicating one switch or circuit is faulty. On Kia it is documented across 2 models: Optima, Sedona.
What are the most common causes of P0504?
The most common causes of P0504 are: Failed brake light switch, Misadjusted brake switch (plunger gap), Wiring/connector fault on one of the two brake switch circuits, Blown brake-circuit fuse affecting one signal, Faulty PCM input. The specific cause varies by vehicle.
How much does it cost to fix P0504 on a Kia?
Repair costs vary widely with the root cause and Kia model; each issue on this page carries its own estimate where one is published.
Looking for P0504 on a different make?
View P0504 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.