P0507 Code: Honda Accord (2018-2023) - Causes, Symptoms & Fixes

Diagnostic guide: P0507 on 2018–2023 Honda Accord

Important data note: There are no owner complaints and no recalls listed for this make/model/year/issue combination in the dataset. That means there are no documented NHTSA complaint counts or recall records to rely on for this exact scenario. The guide below uses general automotive knowledge tailored to Honda Accord 2018–2023, with clear transparency about data limits.

Code meaning and severity

• Meaning: P0507 = Idle Control System RPM Higher Than Normal (engine idle speed higher than expected).
• What it indicates: The engine control module (ECM/ECU) detects idle speed above the target range when the vehicle is at idle. This can be caused by extra air entering the intake, a malfunctioning idle control mechanism (or its electronic equivalent in Honda’s drive-by-wire system), or sensor/engine conditions that cause the ECM to demand more air/fuel than normal.
• Severity: Moderate. A high idle can cause drivability issues (surges, rough idle, stalling at idle) and reduced fuel economy, and it can affect emissions readiness. If left unresolved, it can stress components or mask other problems. Since there are no model-specific fault counts in the provided data, treat this as a condition that warrants diagnosis and repair as needed rather than a common or widespread factory defect.

Common causes on Honda Accord (2018–2023)

• Vacuum leaks in the intake system:
  • Cracked or disconnected vacuum hoses, loose clamps, leaky intake boot, brake booster hose leakage, PCV hose issues.
• Dirty or faulty throttle body or electronic throttle control (ETC) system:
  • Carbon buildup on the throttle plate or throttle body passage.
  • Sticky throttle plate or throttle actuator issues (especially on newer Hondas with drive-by-wire).
• Mass Air Flow (MAF) sensor or MAP sensor issues:
  • Contaminated or failing MAF sensor can misreport air entering the engine.
  • MAP sensor can give incorrect readings if faulty or if there is a manifold leak.
• Idle air control/idle adaptation issues:
  • Although many Hondas use an electronic throttle control with the ECM handling idle, improper idle adaptation or learning can cause high idle if the ECM cannot properly “learn” idle conditions.
• Engine coolant temperature sensor (ECT) or related sensors:
  • If the ECU thinks the engine is colder than it is, it may command a higher idle for cold-start conditions (especially if data is stale or sensor is failing).
• EGR valve or passages:
  • If the EGR system is stuck open or leaking, it can disturb vacuum and cause higher idle in some conditions.
• Intake manifold gasket or runner leaks:
  • A leak near the intake runners can introduce extra air at idle.
• Fuel delivery or fueling trim anomalies (less common for purely high-idle symptoms but possible if the system is compensating for a lean condition):
  • Lean conditions (often indicated by LTFT positive) can accompany or cause drift in idle.

Symptoms typically seen with P0507

• Noticeably higher-than-normal idle speed at rest (often 900–1500 rpm or higher, depending on engine temp and conditions).
• Idle hunting or unstable idle, with the engine “surging” or fluctuating RPM.
• In some cases, rough idle, stumble, or occasional stalling at idle.
• Possible idle-related drivability issues when coming to a stop.
• Possible fuel economy impact if the condition persists.
• Sometimes there are no other dashboard symptoms beyond the check engine light (CEL) or the stored code.

Diagnostic steps (structured approach)

Note: Start with the simplest, least invasive checks and move toward more involved tests. Document data from your scan tool (freeze frame, live data) to guide the process.

A. Confirm the fault and capture data

• Use a capable OBD-II scanner to confirm P0507 is current and not intermittent.
• Record freeze-frame data: idle RPM at fault, engine coolant temperature, throttle position, long-term fuel trim (LTFT) and short-term fuel trim (STFT), rpm vs. commanded idle, and any other codes.
• Check live data when the engine is at idle:
  • Idle RPM vs. target; ECU commanded idle vs. actual.
  • MAF sensor reading (g/s or lb/min) and MAP sensor pressure (kPa or inHg).
  • LTFT and STFT values (positive trims suggest lean bias; negative trims suggest rich bias).
  • Evap or purge system activity if available.

B. Inspect for obvious air leaks and condition of intake/vacuum system

• Visually inspect all intake hoses, clamps, PCV line, brake booster hose, and any vacuum lines for cracks, splits, or disconnections.
• Wiggle test hoses while engine running to check for leaks; listen for changes in idle.
• Perform a smoke test if available or a dedicated vacuum-leak test to locate leaks you can’t see visually.
• Check for intake manifold gasket leaks around the throttle body mounting area and associated gaskets.

C. Inspect throttle/body and idle control/system

• For Honda’s drive-by-wire setup, inspect the throttle body and the electronic throttle control (ETC) system:
  • Look for buildup on the throttle plate; clean the throttle body if dirty, using a manufacturer-approved cleaner.
  • If cleaning does not resolve after proper relearn, consider throttle body service or replacement per service procedure.
• Perform idle relearn if the vehicle requires it after cleaning or service. Some Hondas require a specific procedure: key-on, engine idle for a period, or a short drive cycle to relearn idle.

D. Check sensors that influence air measurement

• MAF sensor:
  • If dirty or contaminated, clean with the appropriate cleaner (do not use a wire brush; use manufacturer-approved cleaner).
  • If cleaning doesn’t resolve the issue and readings remain out of spec, replace the MAF sensor.
• MAP sensor:
  • Inspect the sensor connector and wiring for corrosion or damage.
  • Measure MAP readings at idle and during throttle transitions; compare to spec for your engine.
  • Replace if readings are out of range or there are obvious faults.

E. Check related systems and sensors

• Engine coolant temperature sensor (ECT):
  • Compare ECT reading with coolant temperature; a faulty ECT can cause improper idle and fuel trimming.
• EGR valve and passages:
  • Inspect for sticking or leaks; test or clean if applicable.
• Long-term indications of lean condition (LTFT > +5% to +20% and STFT positive) can point toward vacuum leaks or unmetered air entering the system.

F. Electrical and control logic considerations

• Inspect for loose or corroded electrical connectors to sensors (MAF, MAP, ECT, throttle actuator, ETC).
• Check for recent battery disconnects or PCM reprogramming; some vehicles may need a proper idle relearn or adaptive reset after power events.

G. If no mechanical fault found

• Check for engine misfire conditions (P030X codes) that could coincide with high idle or fuel trim abnormalities.
• Consider a software/ECU update or calibration if applicable (note: no specific Honda TSBs are cited in the provided data; a dealership may verify if any updates apply to your VIN).
• Re-test after repairs and clear codes; drive the vehicle through a normal cycle to verify that idle behavior has stabilized.

Related codes (typical companions or nearby diagnoses)

• P0505 Idle Control System Malfunction (the older reference for idle control issues; in modern Honda engines, idle control is integrated with ETC, but the concept remains relevant if the ECU reports a general idle control fault)
• P0506 Idle Control System RPM Too Low
• P0507 Idle Control System RPM Higher Than Expected
• P0101 MAF Sensor Range/Performance (possible misreadings contributing to wrong air measurement)
• P0106 MAP Sensor Circuit Range/Performance
• P0171/P0174 Lean Condition (can accompany high idle in cases of vacuum leaks or unmetered air)
• P0300–P030X (misfire codes) if an idle problem triggers misfire under idle or if the ECU misreads air/fuel.

Repair options and costs (2025 prices)

Prices are approximate ranges for typical 2018–2023 Accord repairs. Actual prices vary by location, labor rates, dealer vs independent shop, and whether OEM or aftermarket parts are used.

• Vacuum leaks (hose replacement, clamps, PCV hose)
  • Parts: $5–$40
  • Labor: $80–$200
• PCV valve replacement (if applicable)
  • Parts: $5–$20
  • Labor: $40–$100
• Throttle body cleaning (DIY or shop)
  • Parts: often $0–$20 (if DIY cleaning)
  • Labor: $60–$180
• Throttle body replacement (if necessary)
  • Parts: $150–$600
  • Labor: $150–$300
• MAF sensor cleaning or replacement
  • Cleaning (DIY): $0–$5 in cleaners
  • Replacement: $100–$350
• MAP sensor replacement
  • Parts: $40–$150
  • Labor: $60–$120
• EGR valve cleaning or replacement
  • Cleaning: $0–$100 in parts (DIY or shop)
  • Replacement: $250–$900 (parts + labor)
• Intake manifold gasket replacement
  • Parts: $100–$400
  • Labor: $400–$1,200
• Idle control valve (if separate) replacement
  • Parts: $60–$250
  • Labor: $50–$200
• ECU reflash or recalibration
  • Parts: typically included in labor; $0–$100 in some shops
  • Labor: $50–$150
• Brake booster leak (if diagnosed as source)
  • Parts: $30–$150
  • Labor: $100–$350
• Miscellaneous: wires/connectors, clamps, gaskets
  • Parts: $5–$100
  • Labor: $50–$150
• Worst-case scenario (rare): PCM/ECU replacement
  • Parts: $600–$1,200
  • Labor: $150–$400

Warranty note: If your Accord is still under the Honda powertrain, emissions, or factory warranty, some of these repairs may be covered. Check your VIN and consult with an authorized Honda dealer to confirm coverage.

DIY vs professional

• DIY-appropriate tasks (lower risk, educational value, cost-saving potential):
  • Visual/Vacuum hose inspection and simple hose replacements.
  • Throttle body cleaning (with the correct cleaner and care not to drop debris into the intake).
  • MAF sensor cleaning (careful handling; reconnecting wiring after cleaning).
  • PCV valve replacement (simple on many engines).
  • Leaks verification with a smoke test or soapy water routine (if you have the tools, to avoid disassembly).
• Tasks better left to a professional (higher risk, or where proper tools/witness data is required):
  • Throttle body replacement or significant ETC calibration (requires specific procedures and relearn).
  • Intake manifold gasket replacement (requires disassembly, torque specs, gasket sealing).
  • MAP/MAF sensor replacement with proper diagnostic checks.
  • EGR valve cleaning/replacement if the system is integrated with the engine’s emissions control and requires specialized testing.
  • ECU updates, reprogramming, or idle relearn procedures that require a capable scan tool and the correct software.
  • Vacuum leak testing that requires professional smoke testing or advanced diagnostic equipment.

Prevention and maintenance tips

• Regular maintenance to minimize idle problems:
  • Replace air filter on schedule; a clogged filter can affect airflow readings.
  • Inspect and replace cracked vacuum hoses and PCV lines before they fail.
  • Clean MAF sensor and throttle body as part of routine maintenance (not too frequently; follow OEM guidance).
  • Keep the brake booster hose intact and check for leaks if brake performance changes.
  • Use quality fuel and consider fuel system cleaners as recommended by Honda or your mechanic.
• Idle reliability practices:
  • If you notice high idle persistently after a cold start, allow the engine to warm up; some models may idle higher briefly when cold.
  • Do not bypass the idle relearn steps after cleaning the throttle body or changing sensors; perform the idle relearn per the vehicle’s procedure.
  • If an inspection reveals a suspected vacuum leak, address it promptly to avoid lean conditions that can damage the engine or reduce fuel economy.
• Environment and driving habits:
  • Short trips with cold starts can stress idle control learning; combine trips to keep the engine warm longer enough to complete emissions-related cycles.

Data limitations and transparency

• The provided dataset states no NHTSA complaints and no recalls for the 2018–2023 Honda Accord with P0507. This means there is no model/year-specific documented prevalence to cite from NHTSA in this session. That does not rule out real-world occurrences; it only means they aren’t reflected in the dataset you supplied.
• The guide uses general automotive diagnostics knowledge tailored to Honda Accords and typical P0507 failure modes. Real-world outcomes may vary, and there may be model-year specific nuances not captured by the supplied data.
• If you seek model-year specific TSBs or service notices, those would need to be checked directly with Honda and the NHTSA or factory service portal, since they are not present in the provided data.

If you’d like, I can tailor a printable one-page checklist for a shop visit, or convert this into a step-by-step flowchart you can follow with a scanner in hand.