1. What is P0448 in Audi Q5L?

The P0448 OBD-II code stands for EVAP System Purge Control Circuit Short to Ground. For the Audi Q5L (2019-2024)—a top-selling European luxury SUV—this code targets the EVAP purge control valve in its 2.0T EA888 Gen4 engine, standard in 45 TFSI quattro, Premium Plus, and Prestige trims (paired with 7-speed S tronic transmission).

The Q5L’s EVAP system uses the purge control valve to regulate fuel vapor flow from the charcoal canister to the engine (for combustion). The valve is controlled by the ECU via a 12V circuit—normal operation requires 10–14V voltage and 15–30Ω resistance. P0448 triggers when the ECU detects a short (resistance <5Ω) or voltage spike (>16V) in the valve circuit—indicating a faulty valve, damaged wiring, or water intrusion.

Audi Q5L Specific Note: This code is widespread in 2020-2023 Q5L 45 TFSI quattro models, per Audi Technical Service Bulletin (TSB) 22-09-04. The EA888 Gen4’s engine bay layout routes the purge valve harness near the windshield washer fluid reservoir; leaks often short the circuit, leading to P0448.

2. Common Causes of P0448 in 2019-2024 Q5L

P0448 in Audi Q5L EA888 Gen4 models stems from EVAP purge valve circuit shorts—below are real-world cases diagnosed with the ICARZONE UR800:

• Faulty Purge Control Valve (2021 Q5L 45 TFSI quattro): An owner with 58,000 miles reported a "Check Engine" light and rough cold starts. The UR800’s EVAP Valve Test showed resistance 3Ω (normal:15–30Ω). Replacing the valve with OEM #8W0906517A (per TSB 22-09-04) fixed P0448.
• Water-Damaged Wiring (2020 Q5L Premium Plus): A Premium Plus owner’s P0448 reappeared after valve replacement. The UR800’s Circuit Continuity Test found a short—washer fluid leaked onto the harness, corroding wires. Repairing with heat-resistant, water-proof wire (#Dorman 10521) stabilized the circuit.
• ECU Voltage Spike (2019 Q5L Prestige): A Prestige owner’s P0448 occurred after a battery jump. The UR800’s ECU Output Test showed 18V to the valve (normal:10–14V). Reflashing the ECU with Audi firmware v3.6.2 via UR800 resolved the voltage issue.
• Loose Ground Connection (2022 Q5L 45 TFSI): A 45 TFSI owner’s P0448 persisted after wiring repairs. The UR800’s Ground Test showed poor contact at the valve’s ground pin. Cleaning the ground terminal and applying dielectric grease fixed the short.

3. Key Symptoms of P0448 in Q5L EA888

P0448 symptoms in the Audi Q5L focus on EVAP system malfunction and engine performance—watch for these signs that signal circuit shorts:

4. Audi Q5L Trims/Engines Prone to P0448

Audi service data highlights these 2019-2024 Q5L configurations with the highest P0448 occurrence rates (all EA888 Gen4 engines):

5. Diagnose P0448 with ICARZONE UR800

Diagnose P0448 in your Audi Q5L EA888 Gen4 accurately with the UR800’s Audi-specific EVAP tools. Follow these steps (engine off, key in "ON" position; ensure washer fluid reservoir is not leaking):

Case Example: A 2021 Q5L 45 TFSI quattro failed Step 2 (4Ω) and Step 5 (TSB 22-09-04 eligible). The UR800’s Component Location Tool guided valve access (engine bay left, near washer reservoir). Replacing the valve and sealing the reservoir fixed P0448—verified by test drive (smooth starts, no fuel odor).

6. How to Fix P0448 in Audi Q5L

Resolve P0448 in your Q5L with these UR800-verified solutions—tailored to the EA888 Gen4 engine’s EVAP system:

1. Replace EVAP Purge Control Valve (Most Common Fix for TSB 22-09-04)

1. Confirm valve fault via UR800’s Step 2. Locate the purge valve: Engine bay left side, mounted to the intake manifold (2-pin connector, 1 10mm bolt).
2. Disconnect the valve’s electrical connector (press the release tab) and remove the mounting bolt with a socket wrench.
3. Pull the old valve straight out—inspect the inlet/outlet hoses for cracks (replace with OEM hose #8W0133872 if damaged).
4. Install an OEM purge control valve:
   • 2019-2021 Q5L: #8W0906517A
   • 2022-2024 Q5L: #8W0906517B (water-resistant coil upgrade)
   Reattach the hoses and secure with hose clamps.
5. Reinstall the mounting bolt (torque to 8 ft-lbs), reconnect the connector. Clear P0448 with UR800 and run a Valve Activation Test to confirm "click" and normal resistance.

2. Repair Water-Damaged Wiring Harness

1. Confirm wiring issue via UR800’s Step 3. Trace the valve harness from the connector to the ECU (runs near the washer fluid reservoir).
2. Identify corroded or shorted wires—cut out 1.5 inches of damaged section (use wire cutters) and strip 1/4 inch of insulation from both ends.
3. Splice new 18-gauge water-proof, heat-resistant wire (#Dorman 10521) using heat-shrink butt connectors. Crimp connectors and apply heat to seal (no exposed wire).
4. Wrap the repaired harness in water-proof tape (#3M 88 Scotch Super 33+) and secure it away from the washer reservoir with zip ties.
5. Retest continuity with UR800 (Step 3) and clear P0448. Test drive to confirm no voltage spikes or fuel odor.

3. Update ECU Firmware (for Voltage Spikes)

1. Confirm ECU issue via UR800’s Step 4. Connect UR800 to the Q5L’s OBD-II port (under steering wheel) and turn key to "ON."
2. Select "Audi" > "Q5L" > "EA888 Gen4" > "ECU" > "Firmware Update." The tool will detect the current version and download the latest (v3.6.2 for 2019+ models).
3. Do not turn off the key or disconnect UR800 during the update (takes 20–25 minutes). The tool will alert you when complete (ECU reboots automatically).
4. Run UR800’s Step 4 (voltage test) to confirm 10–14V. Clear P0448 and perform a cold start test—ensure the engine starts smoothly without sputtering.

7. P0448 Repair Costs & Maintenance Tips

P0448 repair costs for the Audi Q5L EA888 Gen4 vary by cause. Use this table to budget:

Maintenance Tips for Audi Q5L Owners

• 45 TFSI quattro (urban drivers): Replace the purge valve every 75,000 miles (preventive) — use OEM #8W0906517B for 2022+ models to avoid TSB 22-09-04 water damage.
• Inspect the washer fluid reservoir monthly—replace the cap if cracked (prevents leaks onto the valve harness) and use Audi-approved washer fluid (avoids corrosion).
• Avoid jump-starting the battery unless necessary—use a battery tender for low charge (prevents ECU voltage spikes that short the valve circuit).
• Clean the valve’s ground terminal during oil changes—apply dielectric grease to maintain good contact (critical for humid climates).
• Perform the UR800’s EVAP System Health Check every 15,000 miles — monitor valve resistance and voltage to catch issues before P0448 triggers.

8. Audi Q5L-Specific FAQs