P0441 on 2018-2020 Acura MDX: EVAP Purge Flow Malfunction Causes & Fixes

What's Unique About the 2018-2020 Acura MDX

The 2018-2020 Acura MDX is known to have a specific manufacturing defect that causes code P0441. Acura has acknowledged in official service bulletins that variations in the spring inside the purge control solenoid valve can cause it to wear unevenly and stick. This makes the purge valve the overwhelmingly likely point of failure, unlike in other vehicles where the cause might be a wider range of possibilities like leaks or sensor issues.

Diagnostic Flowchart

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Symptoms You May Notice

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• Check Engine Light is on
• Dashboard message "Emission Systems Problem".
• In some cases, an "Electric Parking Brake Problem" message may appear simultaneously.
• In rare cases, a faint fuel smell
• Slightly rough idle in some instances.

Most Likely Causes

1. Faulty EVAP Purge Control Solenoid Valve 🔴 High Probability Acura issued Technical Service Bulletin #B23-035 stating that "Due to variations in the purge control solenoid valve spring, the valve wears unevenly and intermittently sticks." This known defect is the primary cause of P0441 on this specific vehicle. [6, ⭐ MANUFACTURER TSB — highest authority, OWNER COMPLAINT]
   How to confirm: Use a scan tool to command the purge valve to open and close while monitoring vacuum flow. 🎬 See this guide for troubleshooting EVAP system flow issues A simpler method, given the high probability and low part cost, is to replace the part, as testing can sometimes be inconclusive if the valve only sticks intermittently.
   Typical fix: Replace the purge control solenoid valve assembly. This is a simple repair involving removing the engine cover, disconnecting a hose and an electrical connector, and removing the valve. 🎬 Watch: A pro mechanic's walkthrough for replacing the purge valve
   Est. part cost: $35-$60
2. Blocked or Cracked EVAP Hose ⚪ Low Probability
   How to confirm: Visually inspect all hoses connected to the purge valve and charcoal canister for cracks, brittleness, or disconnections. A smoke test can be performed to find leaks that are not visible.
   Typical fix: Replace the damaged hose section.
   Est. part cost: $10-$30
3. Faulty or Loose Gas Cap ⚪ Low Probability The 2018-2020 MDX uses a capless fuel filler system. While less common, debris in the filler neck seal can prevent a proper seal, contributing to EVAP system pressure issues.
   How to confirm: Inspect the fuel filler neck for any debris or damage to the internal flap and seal. Clean it carefully with a cloth.
   Typical fix: Clean the fuel filler neck seal. If the seal is damaged, the filler neck assembly may need replacement.
   Est. part cost: $0-$150

Rare But Worth Checking

• Faulty Charcoal Canister: This can happen if the fuel tank is consistently overfilled, which forces raw fuel into the canister, saturating the charcoal and causing a blockage.
• Faulty Fuel Tank Pressure (FTP) Sensor: If the sensor that measures EVAP system pressure fails, it can send incorrect data to the ECM, triggering a false P0441 code. This will usually be accompanied by other sensor-specific codes.

Diagnosis Steps

1. Verify Technical Service Bulletins (TSBs): Confirm TSB #B23-035 applies. Given the known issue, this is the most important first step. [6, ⭐ MANUFACTURER TSB — highest authority]
2. Inspect and Clean Fuel Filler Neck: Check the capless fuel filler neck for debris and ensure the flap seals correctly.
3. Locate the Purge Control Solenoid Valve: It is found on the engine, near the intake manifold. Remove the plastic engine cover for access.
4. Test the Purge Valve: The most definitive test is to use a bidirectional scan tool (like the dealer's i-HDS) to command the valve open and closed, checking for vacuum flow. However, since the failure is intermittent, the valve may test fine but still be faulty.
5. Replace the Purge Valve: Due to the high probability of failure confirmed by the TSB and numerous owner reports, replacing the purge valve is the most direct and often most cost-effective step. It involves disconnecting the electrical connector, a vacuum hose, and removing the valve.
6. Inspect Hoses: While replacing the valve, inspect the connected vacuum hoses for any cracks or brittleness.
7. Clear Codes and Test Drive: After replacement, clear the DTC with a scan tool and drive the vehicle to ensure the code does not return. The dealer procedure includes running an EVAP function test with the i-HDS tool.

Parts You'll Likely Need

• EVAP Purge Control Solenoid Valve (OEM #36162-5G0-A01) — This is the specific part identified by Acura in TSB #B23-035 as having a manufacturing defect (faulty spring) that causes it to stick and trigger code P0441. The TSB lists the original failed part as 36162-5G0-A01 and the replacement part as 36162-5G0-A02. [6, ⭐ MANUFACTURER TSB — highest authority]
  Trusted brands: Acura (OEM), Dorman, Standard Motor Products
  OEM price range: $35-$50
  Aftermarket price range: $25-$45

Related Codes That Often Appear With This One

• P04F1 — P04F1 indicates 'EVAP System Low Purge Flow'. This code is a direct companion to P0441 ('Incorrect Purge Flow') and is often triggered by the same faulty purge valve that is either stuck closed or not opening sufficiently. [OWNER COMPLAINT, 16]

Technical Service Bulletins (TSBs) & Recalls

• B23-035: 'MIL Comes on with DTC P0441' - Identifies the faulty purge control solenoid valve spring as the cause and provides the replacement procedure and updated part number (36162-5G0-A02). [6, ⭐ MANUFACTURER TSB — highest authority]
• BPaS04222021902: 'Request for Parts: 2018-2020 MDX & TLX V6 MIL On w/ DTC P0441 Stored' - An earlier request from Honda/Acura to investigate the root cause of this specific code on these vehicles. [27, ⭐ MANUFACTURER TSB — highest authority]

Platform-Specific Known Issues

• Acura issued TSB #B23-035 for 2018-2020 MDX models (among others) for DTC P0441. The bulletin explicitly states the cause is a variation in the purge control solenoid valve spring, leading to uneven wear and intermittent sticking. [6, ⭐ MANUFACTURER TSB — highest authority]
• Prior to issuing a fix, Acura was actively investigating this issue under TSB #BPaS04222021902, requesting dealerships to collect parts from affected vehicles with over 15,000 miles to better understand the cause. [27, ⭐ MANUFACTURER TSB — highest authority]

Mechanic-Grade Diagnostic Values

• EVAP Purge Control Solenoid Valve Resistance — expected: Approximately 20-30 Ohms at room temperature.. Failure: A reading of infinite resistance (open circuit) or very low resistance (short circuit) indicates a failed solenoid coil.
• Voltage at Purge Control Solenoid Connector — expected: Battery voltage (approx. 12V) on one pin with the key on, engine off. The other pin is the ground, controlled by the ECM.. Failure: No voltage indicates a wiring or fuse issue. The presence of voltage but a non-functioning valve points to a bad valve or a problem with the ECM's ground signal.

Scan Tool Commands That Help

• Acura i-HDS (Honda Diagnostic System): EVAP Test — This is the final verification step required by Acura's TSB #B23-035 after replacing the purge control solenoid valve. It runs a full system function test to confirm the repair is successful and that no other issues are present.
• Bidirectional Scan Tool: EVAP Purge Valve Actuation Test / On-Off Command — Used during diagnosis to manually command the purge valve to open and close. While the engine is running, a technician can command the valve open and feel for vacuum at the inlet port to confirm it is mechanically functioning. However, this may not catch an intermittent sticking issue as described in the TSB.

Wiring & Ground Locations

• EVAP Purge Control Solenoid Connector — On the engine, near the intake manifold, connected directly to the purge valve.. This 2-pin connector provides power and the control signal from the ECM. A poor connection, corrosion, or damaged wire at this connector will prevent the valve from operating correctly, mimicking a failed valve and triggering P0441.

Real Owner Repair Stories

• Reddit user in r/Acura (2020 Acura MDX) — Check engine light with dashboard messages "Emission Systems Problem" and "electric braking problem". Code P0441 was read by a parts store.
  ❌ Tried (didn't work) Cleaning the capless fuel filler neck.
  ✅ What actually fixed it The issue was resolved by replacing the EVAP purge control solenoid valve. Another user cited Acura TSB #23-035 and provided the updated part number (36162-5G0-A02) as the definitive fix for the known intermittent sticking problem.

OEM Part Supersession History

• 36162-5G0-A01 → 36162-5G0-A02 — The original part was identified as having a manufacturing defect. TSB #B23-035 states variations in the valve's internal spring cause it to wear unevenly and stick intermittently, leading to the P0441 code. The new part number is the corrected component.