P0556 on 2016-2017 Dodge Durango: Brake Booster Pressure Sensor Causes and Fixes

What's Unique About the 2016-2017 Dodge DURANGO

For the 2016-2017 Dodge Durango and its platform-mate, the Jeep Grand Cherokee (WK2), the appearance of P0556 is specifically addressed in Technical Service Bulletins (TSBs) 18-024-17 REV. C and 18-049-20. These bulletins indicate that the code may appear alongside other specific DTCs (like P040B, U1424, P06EF) and that a PCM software update could be the required fix, rather than a hardware replacement. This suggests that the vehicle's control module logic may be overly sensitive or misinterpreting sensor data under certain conditions, a known issue that FCA resolved with a reflash.

Diagnostic Flowchart

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

Symptoms You May Notice

• Check Engine Light is on
• Brake warning light may be illuminated
• Hard brake pedal requiring more effort to press
• Increased stopping distances
• Hissing noise from the brake booster area
• Engine may stall when applying the brakes

Most Likely Causes

1. PCM Software Update Needed 🔴 High Probability Manufacturer TSBs #18-049-20 and #18-024-17 REV. C explicitly link P0556 with other codes and state the fix is to reprogram the PCM with the latest software. This is a known logic issue for 2016-2017 Durango and Grand Cherokee models.
   How to confirm: Check with a Dodge dealership or a qualified shop with access to OEM software (wiTECH) to see if the vehicle's PCM has the latest updates installed. This should be the first step if codes P06EF, P040B, or U1424 are also present, as mentioned in the TSBs.
   Typical fix: Updating the Powertrain Control Module (PCM) software. The TSB notes this is a 0.2-hour labor operation.
   Est. part cost: $0
2. Faulty Brake Booster Pressure Sensor 🔴 High Probability → Shop Power Brake Booster The sensor is a common failure point across many vehicles and is often the primary hardware culprit when a software update doesn't apply or resolve the issue. Internal failure or contamination can cause the voltage signal to drift out of its expected range.
   How to confirm: Using a scan tool, monitor the live data from the sensor. The voltage should change smoothly as the brake pedal is applied and released (typically between 0.5V and 4.5V). If the reading is stuck, erratic, or doesn't change, the sensor is likely bad. The sensor has a 3-pin connector.
   Typical fix: Replace the brake booster pressure sensor and the rubber grommet it sits in. The sensor is typically located directly on the brake booster housing.
   Est. part cost: $30-$70
3. Vacuum Leak 🟡 Medium Probability Vacuum hoses, particularly the main line to the booster, can become brittle and crack over time due to heat and age, causing a loss of vacuum.
   How to confirm: Visually inspect all vacuum hoses connected to the brake booster for cracks, splits, or loose connections. Listen for a hissing sound near the booster at idle. A smoke test can also be performed to pinpoint hard-to-see leaks. A faulty one-way check valve in the booster supply hose can also be a cause.
   Typical fix: Replace the damaged vacuum hose or the one-way check valve in the booster supply hose.
   Est. part cost: $15-$50
4. Wiring or Connector Issue ⚪ Low Probability
   How to confirm: Visually inspect the sensor's electrical connector and wiring harness for any signs of corrosion, damage, or loose pins. Use a multimeter to check for proper voltage and ground at the connector.
   Typical fix: Clean the connector with electrical contact cleaner or repair the damaged section of the wiring harness.
   Est. part cost: $5-$25

Rare But Worth Checking

• Failing Brake Booster: → Shop Power Brake Booster While less common, an internal diaphragm leak in the brake booster itself can cause this code. This is usually accompanied by a persistent hissing sound after the engine is shut off and a very hard pedal.
• Faulty Powertrain Control Module (PCM): This is extremely rare. The PCM should only be considered after all other possibilities, including the official software updates, have been exhaustively ruled out.

Diagnosis Steps

1. Check for Technical Service Bulletins (TSBs). Using the VIN, confirm with a dealer if TSBs #18-049-20 or #18-024-17 REV. C apply and if the recommended PCM update has been performed. This is the most critical first step.
2. Scan the PCM for any other stored trouble codes. Note if P06EF, P040B, U1424, or P2299 are present, as this strongly indicates the TSB software fix is needed.
3. If software is up to date, perform a thorough visual inspection of the brake booster, the pressure sensor, and all connected vacuum lines. Look for obvious signs of damage, cracks, or disconnections.
4. Inspect the electrical connector and wiring at the pressure sensor for corrosion, damage, or loose connections.
5. With a scan tool, observe the live data for the brake booster pressure sensor. The voltage should respond logically to brake pedal application, typically sweeping between 0.5V and 4.5V.
6. If a scan tool is unavailable, use a vacuum gauge to test the vacuum being supplied to the booster. It should be strong and steady at idle (usually 18-22 inHg).
7. If vacuum supply is good and the sensor signal is faulty, test the sensor's circuit for power, ground, and signal integrity at the 3-pin connector before condemning the sensor.
8. If the sensor and circuit test good, but vacuum is low or bleeds off, perform a smoke test to find the source of the leak, which could be a hose, check valve, or the booster itself.

Parts You'll Likely Need

• Brake Booster Pressure Sensor (OEM #68249823AB) — This sensor is the most common hardware component to fail after the software has been ruled out. It is responsible for sending incorrect readings to the PCM.
  Trusted brands: Mopar, Standard Motor Products (BST157), Duralast, Wells (5S17531)
  OEM price range: $50-$90
  Aftermarket price range: $30-$70

Related Codes That Often Appear With This One

• P06EF — Listed in TSB #18-049-20 as a code that can be set along with P0556, often related to a needed PCM software update for Engine Restart Performance.
• P040B — Mentioned in both TSB #18-049-20 and #18-024-17 REV. C as a related code for EGR Temperature Sensor Performance, pointing towards a common software issue.
• U1424 — Also cited in both TSBs as a code that may appear with P0556 for 'Implausible Engine Torque Signal', indicating a potential PCM software calibration issue.
• P2299 — This code for 'Brake Pedal Position/Accelerator Pedal Position Incompatible' is also listed in the same TSBs, suggesting the software update addresses multiple pedal and braking-related logic faults.

Technical Service Bulletins (TSBs) & Recalls

• 18-049-20: Supersedes the previous TSB. Involves reprogramming the PCM with the latest software to address P0556 and other codes like P06EF and P040B on 2016-2017 Durango and Grand Cherokee models.
• 18-024-17 REV. C: Also lists P0556 as a potential DTC that may be set, indicating a known issue recognized by the manufacturer that can be fixed with a PCM software flash. This TSB applies to vehicles built on or before March 06, 2017.

Platform-Specific Known Issues

• NHTSA Technical Service Bulletin #18-049-20 and #18-024-17 REV. C indicate that P0556 may be set on 2016-2017 Dodge Durangos, potentially along with codes P06EF, P040B, and U1424. The fix may require a PCM software update. This applies to vehicles with the 3.6L, 5.7L, and 3.0L engines.
• The issue is not exclusive to the Durango; its platform-mate, the 2016-2017 Jeep Grand Cherokee (WK2), is also covered under the same TSBs for the same set of fault codes.