What Does P0172 Mean on Your 2024 Volvo XC40?
A P0172 code on your 2024 Volvo XC40 signals that the powertrain control module has detected a fuel mixture that is too rich on Bank 1. The 2024 XC40 is powered by a 2.0-liter turbocharged four-cylinder engine with the B4 (194 hp) or B5 (247 hp) mild-hybrid powertrain, featuring Volvo's 48-volt integrated starter-generator system. Running too rich means excess fuel is being injected relative to the amount of air in the combustion chambers, hurting fuel economy and increasing harmful emissions.
Symptoms You May Notice
- Check engine light on
- Fuel economy dropping below the normal 23-32 MPG range
- Black smoke from the exhaust
- Rough or lumpy idle
- Strong fuel odor at the tailpipe
- Hesitation during acceleration
Most Common Causes of P0172 on the 2024 XC40
- Fouled Mass Airflow (MAF) Sensor - Contamination from oil vapors and dust affects the MAF sensor reading, making the ECM think less air is entering the engine and adding extra fuel to compensate.
- Leaking Fuel Injectors - The direct-injection fuel injectors on the 2.0L engine operate at high pressures. A small leak or failure to seal properly results in excess fuel in the combustion chamber.
- Failing Upstream O2 Sensor - A degraded oxygen sensor on Bank 1 provides inaccurate data about exhaust gas composition, leading the ECM to over-enrich the fuel mixture.
- Dirty Air Filter - An overly dirty air filter chokes off airflow to the turbocharged engine, shifting the air-fuel ratio rich.
How to Diagnose the Problem
Use an OBD-II scanner to confirm the P0172 code and check for any companion codes. Review freeze frame data for the conditions when the code was set. Pull up Bank 1 fuel trim data. Short-term fuel trim swinging heavily negative and long-term fuel trim below -8% to -10% confirm a persistent rich condition. Check the air filter first, as it is the simplest component to inspect. Clean or test the MAF sensor. Verify fuel pressure is within spec using a fuel pressure gauge. Use the scan tool to monitor the upstream O2 sensor on Bank 1 for proper switching behavior.
Repair Options and What to Expect
On the 2024 XC40, start with the easiest repairs first. Clean the MAF sensor using MAF cleaner spray, which takes just 15 minutes. If the sensor is faulty, replacement is a quick job. Fuel injector replacement on the direct-injection engine is a shop-level repair taking 2-3 hours. O2 sensor replacement is accessible from underneath and takes about an hour. Air filter replacement is a fast DIY task requiring no tools on most models.
Estimated Repair Costs
- MAF Sensor Replacement: $150 - $340 (parts and labor)
- Fuel Injector Replacement: $300 - $680 (parts and labor)
- O2 Sensor Replacement: $190 - $420 (parts and labor)
- Air Filter Replacement: $25 - $55 (DIY)
Being a compact luxury SUV, XC40 repair costs are somewhat lower than larger Volvo models. Independent European car specialists typically charge 25-35% less than dealer rates.
Prevention Tips
- Change the air filter every 15,000 miles per the maintenance schedule
- Use quality fuel recommended for the turbocharged engine
- Have the MAF sensor inspected during routine services
- Do not delay when the check engine light comes on
- Follow the Volvo-recommended maintenance schedule to keep the fuel system in top condition