P0506 on 2015-2016 Ram PROMASTER CITY: Low Idle Causes and Fixes

What's Unique About the 2015-2016 Ram PROMASTER CITY

The 2015-2016 Ram ProMaster City, which is based on the Fiat Doblò, uses the 2.4L Tigershark engine with an electronic throttle body. This code is frequently mentioned in multiple Technical Service Bulletins (TSBs) from Ram, often alongside a dozen other codes. This pattern strongly suggests that the original PCM software was highly sensitive and prone to setting various fault codes, including P0506. Ram's solution in many cases was a software update to correct the logic and prevent false triggers. TSB 18-063-17 REV. A specifically lists enhancements to reduce RPM when shifting into drive or reverse when cold, directly addressing idle control behavior.

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
• Engine idle is lower than normal (e.g., below 650 RPM)
• Rough or vibrating idle
• Engine stalling when coming to a stop or while idling in gear
• Slight hesitation when accelerating from a stop
• Unusual engine vibrations.

Most Likely Causes

1. Dirty Electronic Throttle Body 🔴 High Probability → Shop Fuel Injection Throttle Body Carbon and oil vapor from the PCV system can build up around the throttle plate and in the throttle bore. This restricts the small amount of air needed to maintain a proper idle, causing the RPM to drop below the target. This is a very common issue on the 2.4L MultiAir engine.
   How to confirm: Remove the air intake hose from the throttle body and visually inspect for a ring of black carbon buildup around the edges of the throttle plate and bore.
   Typical fix: Carefully clean the throttle body bore and plate with a dedicated throttle body cleaner and a soft cloth or brush. It is recommended to remove the throttle body (four bolts) for a more thorough cleaning. An idle relearn procedure is required after cleaning.
   Est. part cost: $5-$15 for cleaner
2. Outdated Powertrain Control Module (PCM) Software 🟡 Medium Probability Ram released multiple TSBs (e.g., #18-063-17 REV. A, #18-008-16 REV. B) for the 2015-2016 ProMaster City that address P0506 among a list of other codes. This indicates the original software logic was flawed and could incorrectly trigger the code or fail to adapt to minor carbon buildup. TSB 18-063-17 REV. A specifically includes an enhancement to reduce RPM when shifting into gear when cold, directly related to idle control.
   How to confirm: A Ram dealer or a shop with a wiTECH scan tool can check the current software calibration ID against the latest version available from the manufacturer. DIYers with advanced tools like AlfaOBD may also be able to check this.
   Typical fix: Reprogramming (flashing) the PCM with the latest software. This is a dealer-level repair.
   Est. part cost: $0 (if under warranty) - $200
3. Vacuum Leak ⚪ Low Probability While a vacuum leak more commonly causes a high idle (P0507), a small, intermittent leak or a malfunctioning PCV system can confuse the PCM's idle calculations, sometimes resulting in a P0506 code. Common leak points on the 2.4L Tigershark include the intake manifold gasket and PCV hoses.
   How to confirm: Visually inspect all vacuum hoses and the intake manifold for cracks or loose connections. A smoke test is the most effective way to find a leak by forcing smoke into the intake and watching where it escapes.
   Typical fix: Replace the leaking hose, gasket, or component (e.g., PCV valve/hose, intake manifold gasket).
   Est. part cost: $10-$150

Rare But Worth Checking

• Failing Electronic Throttle Body: → Shop Fuel Injection Throttle Body If cleaning the throttle body doesn't resolve the issue and the software is up to date, the internal motor or position sensor may be failing. This is less common than a simple cleaning but is the next logical step.
• Restricted Air Intake or Exhaust: A severely clogged engine air filter or a blockage in the exhaust system (like a failing catalytic converter) can choke the engine, causing idle speed to drop. This is usually accompanied by other symptoms like a major loss of power.

Diagnosis Steps

1. Check for any Technical Service Bulletins (TSBs) related to your vehicle's VIN. This is a critical first step for the ProMaster City, as a software update is a very common fix.
2. Scan for other DTCs. Codes like P0507, P0171, or P0441 can provide clues to the root cause.
3. Inspect the air intake tube between the air filter and the throttle body for any cracks or loose connections.
4. Remove the intake tube and visually inspect the electronic throttle body for carbon buildup. If dirty, remove the throttle body (4 bolts) and clean it thoroughly with appropriate cleaner and a soft brush.
5. After cleaning and reinstalling, perform an idle relearn procedure. A common manual procedure is to turn the ignition to 'On' (engine off) for one minute, then slowly press the accelerator pedal to the floor and release it, then turn the ignition off before starting the engine. Alternatively, simply letting the engine idle for 10-15 minutes may allow the ECU to relearn.
6. If the problem persists, check for vacuum leaks using a smoke machine, paying close attention to the PCV hoses and intake manifold gaskets.
7. If no physical faults are found, consult a dealer to verify if the PCM software is the latest version. If not, have it reflashed per the relevant TSB.

Parts You'll Likely Need

• Electronic Throttle Body (OEM #68253525AA) — While cleaning is usually sufficient, if the internal electronics fail, the entire unit must be replaced. This is the primary component responsible for idle control.
  Trusted brands: Mopar, Bosch, Standard Motor Products
  OEM price range: $250-$400
  Aftermarket price range: $150-$250
• Throttle Body Cleaner — This is the most common fix. Carbon buildup restricts airflow, and a specific solvent is needed to clean it without damaging sensors.
  Trusted brands: CRC, Berryman, WD-40
  OEM price range: N/A
  Aftermarket price range: $5-$15

Related Codes That Often Appear With This One

• P0507 — Idle Speed Performance Higher Than Expected. P0506 and P0507 often appear together in TSBs for this vehicle, suggesting the PCM software has trouble regulating idle in both directions.
• P0171 — Fuel System 1/1 Lean. A vacuum leak can cause both a lean condition and an idle control problem. This code is also listed alongside P0506 in TSB #18-008-16 REV. B and #18-063-17 REV. A.
• P0441 — EVAP Purge System Performance. A faulty EVAP purge valve can sometimes stick open, creating a vacuum leak that affects idle speed. This code is mentioned with P0506 in TSBs #18-008-16 REV. B and #18-063-17 REV. A.
• P0133 — O2 Sensor 1/1 Slow Response. This is another code frequently bundled with P0506 in manufacturer software updates, indicating a related diagnostic sensitivity issue.
• P050D — Cold Start Rough Idle. This code is also addressed in the same software updates (TSB #18-063-17 REV. A and #18-008-16 REV. B), pointing to a broader issue with idle stability during cold starts that the PCM flash aims to fix.

Technical Service Bulletins (TSBs) & Recalls

• 18-063-17 REV. A: Flash: Powertrain Diagnostic and System Improvements, mentions P0506.
• 18-008-16 REV. B: Flash: Powertrain Diagnostic and System Improvements, mentions P0506.
• 18-030-16: Flash: Powertrain Diagnostic And System Enhancements, mentions P0506.
• 18-048-15 REVA: Flash: Powertrain Diagnostic And System Enhancements, mentions P0506.

Platform-Specific Known Issues

• Multiple TSBs (#18-063-17 REV. A, #18-008-16 REV. B, #18-030-16, #18-048-15 REVA) were issued by Ram to address P0506 via a PCM software update. This is a well-documented issue for the 2015-2016 models and should be considered a primary potential cause.
• The sheer number of unrelated codes fixed by these TSBs (from EVAP to O2 sensors to TCM communication) strongly indicates the original PCM calibration was overly sensitive and prone to false flags.

Mechanic-Grade Diagnostic Values

• MAP Sensor Signal Voltage (Key On, Engine Off) — expected: Approximately 4.5 - 5.0 Volts. Failure: A voltage significantly lower than this range suggests a faulty sensor or wiring issue. This reading reflects barometric pressure.
• MAP Sensor Signal Voltage (Engine Running at Idle) — expected: 1.0 - 2.0 Volts. Failure: Voltage that remains high (near the KOEO reading) or is too low (below 1.0V) at idle suggests the sensor is not reading engine vacuum correctly.
• Minimum Throttle Position Sensor (TPS) Voltage — expected: Approximately 0.5 to 1.5 VDC. Failure: A reading outside this range at closed throttle can indicate a miscalibrated or faulty throttle body.

Scan Tool Commands That Help

• wiTECH or AlfaOBD: Throttle Body Relearn / ETC Relearn — This function is required after cleaning or replacing the electronic throttle body to reset its learned idle and off-idle positions. Failure to perform this can cause persistent high or low idle issues.
• Manual Procedure: Accelerator Pedal Relearn Procedure — As a DIY alternative if a scan tool is not available. Turn ignition to 'ON' (engine off), wait for dash lights to cycle, slowly press the accelerator to the floor and hold for 10 seconds, then slowly release. Cycle ignition off. This helps the PCM relearn the pedal's range, which is related to throttle control.
• Manual Procedure: Idle Relearn Procedure — After a battery disconnect or throttle service, simply starting the engine and letting it idle for 10-15 minutes without touching the accelerator can allow the PCM to automatically relearn the idle strategy.

Wiring & Ground Locations

• Primary Engine/Transmission Ground Strap — A braided ground strap connecting the transmission case to the chassis frame rail, often near the driver's side transmission mount. It may be visible by removing the driver's side headlight assembly.. A poor or corroded main engine ground can cause inconsistent sensor readings and erratic behavior from electronically controlled components like the throttle body, leading to various codes including idle control faults.
• Battery Location — Under the driver's side floor mat, beneath a removable access panel.. Due to its unconventional location, battery terminals and ground connections can be overlooked during diagnosis. A loose or corroded connection here can cause system-wide voltage issues affecting the PCM and throttle body.
• Engine Wiring Harness — Runs across the top and sides of the engine, connecting to all sensors, injectors, and the throttle body. Part number 68531763AA is listed for 2015-2017 models.. Rodent damage and chafing on sharp edges of the engine block or brackets are potential points of failure for the throttle body wiring, which can cause intermittent shorts or opens, triggering P0506.

Real Owner Repair Stories

• YouTube channel 'World Mechanics' (2015-2020 Ram ProMaster City with 2.4L MultiAir engine) — Check Engine Light with codes P0506 and/or P0507.
  ✅ What actually fixed it The video identifies the most common cause for both P0506 (idle too low) and P0507 (idle too high) on this specific engine is significant carbon buildup inside the electronic throttle body. A thorough cleaning of the throttle plate and bore resolved the issue.

OEM Part Supersession History

• 68265960AA → 68472070AA — Updated part for the battery ground cable.