P0175 on the 2018 Chevrolet Silverado 1500
A P0175 code on your 2018 Silverado 1500 means the ECM has detected a rich condition on Bank 2 (passenger side). The 2018 Silverado is the last year of the third generation (K2XX) and was available with the 4.3L V6 (285 hp), 5.3L V8 L83 (355 hp), and 6.2L V8 L86 (420 hp). With most 2018 models now at 70,000-130,000 miles, wear-related causes dominate the P0175 diagnosis. These are proven engines with well-documented repair procedures.
High-Mileage Considerations
At this mileage range, multiple components are approaching the end of their service life simultaneously. O2 sensors, MAF sensors, fuel injectors, and vacuum components all wear with age and use. The 5.3L L83 uses direct injection only (no port injection backup), which makes carbon buildup on intake valves and injectors a significant concern at higher mileage. The 6.2L L86 has the same characteristics.
Symptoms
- Check engine light active
- Significantly worse fuel economy than when new
- Black exhaust smoke, especially under throttle
- Rough V8 idle
- Reduced towing power and capability feel
- Failed emissions test
- Strong fuel smell from exhaust
Causes Ranked
1. Worn Bank 2 O2 Sensor
At 70,000+ miles, the upstream O2 sensor on Bank 2 is the primary suspect. Years of thermal cycling, road salt exposure, and exhaust gas contaminants degrade the sensor element. A worn sensor responds slowly and may be biased, causing the ECM to consistently over-fuel. Replacing the O2 sensor is the most common and cost-effective repair for P0175 on high-mileage Silverados.
2. Contaminated or Failed MAF Sensor
After years of service, the MAF sensor may need more than cleaning. At very high mileage, the sensor element itself can degrade and lose accuracy even when clean. Start with cleaning, but if fuel trims do not normalize, replace the MAF sensor. On the Silverado, this is an accessible and affordable repair.
3. Carbon-Fouled Direct Injectors
The 2018 Silverado V8s use direct injection without port injection assistance. By 80,000+ miles, carbon deposits on injector tips can significantly alter spray patterns. Carbon also builds up on the back of intake valves, restricting airflow to specific cylinders. A professional walnut blasting service cleans the valves, and injector cleaning or replacement addresses the injector tips.
4. Exhaust Manifold Bolt Failure
The 2018 Silverado V8s are well-known for exhaust manifold bolt failures. The bolts crack from repeated thermal expansion and contraction, creating an exhaust leak at the manifold. This leak introduces air near the O2 sensor, causing it to read lean, which makes the ECM add fuel. The telltale cold-start ticking noise that fades when warm is a strong indicator of this issue.
Diagnostic Process
- Scan for all codes including misfire and catalyst efficiency codes
- Listen for cold-start exhaust manifold ticking on Bank 2
- Monitor fuel trims on both banks at idle and 2,500 RPM
- Clean the MAF sensor and retest
- Test Bank 2 O2 sensor switching rate with live data
- Visually inspect Bank 2 exhaust manifold bolts
- Check fuel pressure and injector balance
- Consider carbon buildup inspection if other causes are ruled out
Repair Costs
O2 sensor: $100-$250. MAF sensor: $80-$200 (replacement). Exhaust manifold bolt repair: $200-$700 depending on bolt extraction difficulty. Injector cleaning: $100-$200 professional. Carbon cleaning (walnut blast): $300-$600. At this age, the 2018 Silverado is well out of warranty, so compare independent shop and dealer prices.
Worth Fixing?
Absolutely. The most common P0175 repairs cost $100-$300. The Silverado is a truck built to last well beyond 200,000 miles with maintenance. Fixing P0175 protects the catalytic converter ($1,000-$3,000), restores fuel economy, and keeps the truck running at full capability for towing and hauling.