P0441 on 2018 Acura RDX: EVAP Incorrect Purge Flow Causes and Fixes

What's Unique About the 2018-2018 Acura RDX

For the 2018 Acura RDX and its platform mates, this code is not a mystery. Acura has officially acknowledged a manufacturing defect in Technical Service Bulletin (TSB) B23-035. The bulletin states that variations in the internal spring of the original purge control solenoid valve (part #36162-5G0-A01) can cause it to wear unevenly and stick, triggering the P0441 code. This makes the purge valve the overwhelmingly likely point of failure, far more so than on other vehicles where a P0441 code might require extensive leak testing.

Symptoms You May Notice

• Check Engine Light (MIL) illuminated on the dashboard.
• An 'Emissions System Problem' message may appear on the multi-information display.
• In some cases, other unrelated warning lights (like for the electric parking brake or braking system) may appear simultaneously due to system communication logic, even though the root cause is the EVAP system.

Most Likely Causes

1. Faulty EVAP Purge Control Solenoid Valve 🔴 High Probability → Shop Vapor Canister Acura TSB B23-035 confirms a manufacturing defect in the original valve's internal spring, causing it to stick. The TSB specifies replacing the original part (36162-5G0-A01) with the updated part (36162-5G0-A02).
   How to confirm: Given the TSB, direct replacement is the most common and practical diagnostic approach. A technician could use a bidirectional scan tool to command the valve open and closed while monitoring EVAP system pressure, but the failure is often intermittent and may not be caught during a test.
   Typical fix: Replace the EVAP Purge Control Solenoid Valve with the updated OEM part, #36162-5G0-A02.
   Est. part cost: $40-$60

Rare But Worth Checking

• Clogged or damaged charcoal canister: → Shop Vapor Canister This typically only happens if the fuel tank is consistently overfilled, forcing liquid fuel into the canister and saturating the charcoal media. A crack in the canister housing can also cause a leak.
• Cracked or disconnected EVAP hoses: While possible, the hoses are generally durable. A visual inspection for cracks or loose connections, especially at the nipples of the purge valve itself, is worthwhile but this is not the primary suspect for this specific vehicle.
• Faulty Fuel Tank Pressure (FTP) Sensor: → Shop Fuel Tank If the sensor providing pressure data to the computer fails, it can trigger a false code. However, this will usually be accompanied by other sensor-specific fault codes.
• Debris in capless fuel filler neck: → Shop Fuel Filler Neck The 2018 RDX has a capless fuel filler system. While a faulty seal here is more likely to cause a leak code (like P0455/P0456), it's worth inspecting the flap for debris or damage that could prevent a proper seal.

Diagnosis Steps

1. Verify the code with an OBD-II scanner. Confirm P0441 is present.
2. Acknowledge Acura TSB B23-035, which identifies the purge control solenoid valve as the most probable cause for this specific vehicle and code.
3. Locate the purge control solenoid valve in the engine bay. After removing the plastic engine cover, it is mounted on the front of the intake manifold, with two hoses and one electrical connector.
4. Visually inspect the hoses connected to the valve for any obvious cracks or disconnections. Pay close attention to the ends of the hoses where they connect to the valve, as this is a common point for small cracks to develop.
5. Given the high probability from the TSB, the most practical and time-effective step is to replace the purge control solenoid valve.
6. To replace, first remove the engine cover (typically pulls straight off). Disconnect the electrical connector by pressing the tab. Use pliers to release the clamps on the two EVAP hoses and slide them off the old valve.
🎬 Watch: This step-by-step guide shows you how to swap the valve.
7. Remove the old valve from its mounting bracket (often a single 10mm bolt or it may slide off).
8. Install the new valve (Part No. 36162-5G0-A02), reconnect the hoses and electrical connector, and reinstall the engine cover.
9. Clear the trouble code with the OBD-II scanner. Drive the vehicle to allow the onboard computer to run its self-tests and confirm the fix. The dealer procedure also includes running an EVAP function test with a proprietary i-HDS tool, but this is not typically necessary for a DIY repair.

Parts You'll Likely Need

• EVAP Purge Control Solenoid Valve (OEM #36162-5G0-A02) — This is the updated component identified by Acura in TSB B23-035 to fix a known manufacturing defect in the original part (36162-5G0-A01) that causes the P0441 code.
  Trusted brands: Acura / Honda (Genuine OEM)
  OEM price range: $40-$60
  Aftermarket price range: $25-$50

Technical Service Bulletins (TSBs) & Recalls

• B23-035: 'MIL Comes on with DTC P0441' - States that due to variations in the purge control solenoid valve spring, the valve wears unevenly and intermittently sticks, causing the code. Applies directly to the 2018 RDX, as well as 2018-20 MDX and 2018-2020 TLX models. Manufacturer service bulletin TSB Bulletin #B23-035 notes that this uneven wear results in setting DTC P0441 (Evaporative Emission (EVAP) System Purge Flow Malfunction).
• A23-091: This is the equivalent Honda TSB for the same issue, covering models like the 2019-22 Pilot, 2019-24 Odyssey, and 2019-23 Ridgeline/Passport, confirming the widespread nature of this part failure.

Platform-Specific Known Issues

• Acura Technical Service Bulletin B23-035 was issued specifically to address the P0441 code on the 2018 RDX (and other models), confirming the purge valve as the root cause.
• The issue is so common that many owners on forums report the 'Emissions System Problem' light appearing along with an 'Electric Parking Brake Problem' light simultaneously, all resolved by replacing this one valve.
🎬 See how this valve fix clears the electric parking brake light.

Mechanic-Grade Diagnostic Values

• EVAP Purge Control Solenoid resistance — expected: 15 to 30 Ohms. Failure: A reading far outside this range indicates a damaged internal coil, requiring valve replacement.
• Voltage at the EVAP Purge Control Solenoid connector (harness side) — expected: Approximately 12V (battery voltage) on one pin with the key in the ON position.. Failure: No voltage suggests a wiring issue, blown fuse, or problem with the power distribution, not the valve itself.
🎬 Watch: A deep dive into troubleshooting EVAP system flow issues.
• Manual vacuum test of the Purge Valve — expected: When removed from the vehicle, the valve should hold vacuum when applied to the intake manifold port and should not allow air to pass through.. Failure: If the valve fails to hold vacuum, it is stuck open. If it holds vacuum but does not release it when 12V is applied to its terminals, it is stuck closed.

Scan Tool Commands That Help

• Acura i-HDS (Honda Diagnostic System): EVAP Function Test — This is the official dealer procedure to verify the entire EVAP system is functioning correctly after replacing a component like the purge valve. It runs a series of automated checks on the system.

Wiring & Ground Locations

• Battery Ground Cable — Connects the negative battery terminal to the vehicle chassis.. While not a common cause for P0441, a corroded or loose main ground can cause a variety of unpredictable electrical issues and codes. The OEM part number for the 2018 RDX is 32600-TX4-A00.
• Engine/Transmission Ground Straps — There are typically multiple ground straps, with one located near the transmission mount under the battery area.. A poor engine ground can affect the operation of engine-mounted sensors and solenoids, including the purge valve. Visual inspection for corrosion or looseness is recommended during advanced diagnosis.

Real Owner Repair Stories

• Reddit user in r/Acura (2020 Acura MDX (platform mate with same engine and TSB)) — Check engine light with dashboard messages "Emission Systems Problem" and "electric braking problem". Code P0441 was present.
  ❌ 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 with the updated part number (36162-5G0-A02) as specified in Acura TSB B23-035.

OEM Part Supersession History

• 36162-5G0-A01 → 36162-5G0-A02 — The original part had an internal spring that could wear unevenly, causing the valve to stick intermittently. The updated part corrects this manufacturing defect.
  Heads up: The original part should not be used for replacement as it is known to be defective.

Diagnostic Flowchart

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• U0401-68 — Parking brake system error code. This frequently appears simultaneously with P0441 on this Acura platform due to system communication logic when the EVAP purge valve fails.
• P0496 — EVAP High Purge Flow. Related to the primary failure mode described in TSB B23-035, where the purge valve's internal spring wears unevenly and causes the valve to intermittently stick open.
• P0442 — EVAP System Small Leak Detected. Can be triggered by the same physical inspection points noted for P0441, specifically small cracks developing at the ends of the EVAP hoses where they connect to the purge valve.
• P0455 — EVAP System Large Leak Detected. Related to the EVAP hoses becoming completely disconnected or severely cracked at the purge control solenoid valve mounting point.

Frequently Asked Questions