P0174 on Honda: Causes, Symptoms and Fix Cost
Quick Answer
Safe to drive (short-term)
P0174 on a Honda means the engine is running too lean on Bank 2, the cylinder bank that does not contain cylinder 1. It appears on V6, V8 and boxer engines, and on inline-six engines whose engine management splits the cylinders into two banks with an upstream oxygen sensor each, such as BMW's M54, N52 and N54. The computer added the maximum extra fuel it can (long-term fuel trim past roughly +25 percent) but still measured too much air against the ideal 14.7:1 ratio. The most common cause is an unmetered air leak: a cracked vacuum hose or leaking gasket. The cheapest fixes, a MAF clean or a split vacuum hose, can cost under 100 euros; a gasket or PCV repair runs roughly 40 to 260 euros.
- Severity
- Moderate · Fuel System
- Typical repair cost, all makes
- €30-€700
Connect a standard OBD2 adapter (Bluetooth LE on iPhone) to your Honda and Skanyx tells you what P0174 means on that engine, whether it is safe to keep driving, and what the fix should cost. Free on iPhone and Android.
Get Skanyx freeWhat does P0174 mean on a Honda?
The Quick Answer above is the generic definition. What follows is the model-specific detail for the Honda models that log P0174.
Honda Civic
2006-2024
Nearly every Civic is an inline-four with a single bank, so it sets P0171 rather than P0174. If a scan tool reports P0174 on an inline-four Civic, treat it as suspect and re-scan with a second tool or clear and recheck, because there is no physical Bank 2. The genuine lean causes on a Civic (PCV, vacuum hoses, dirty MAF) still apply, just under P0171.
What causes P0174 on a Honda?
Beyond the generic causes listed on the main P0174 page, these are the patterns noted for Honda models:
P0174 is effectively impossible on the inline-four (single-bank) Civic
: Honda Civic
A reported P0174 is usually a scan-tool misread; verify against P0171 instead
: Honda Civic
How to diagnose P0174 on a Honda with OBD2
- Check whether P0171 is also stored. Both codes together points to a whole-engine cause (dirty MAF, low fuel pressure, or a large central vacuum leak), not a Bank 2-specific fault, so start there
- Read short-term and long-term fuel trims on Bank 2 with a scan tool. A long-term trim sustained above about +10 percent shows the bank is correcting for a lean mixture, and the code typically sets near the ECU's limit of around +25 percent; trims that worsen at idle suggest a vacuum leak, trims that worsen under load suggest a fuel-delivery problem
- Smoke-test the intake, or spray a small amount of carburettor cleaner around the Bank 2 intake manifold gaskets, vacuum hoses, and PCV connections, watching for an RPM change that pinpoints the leak
- Inspect and clean the MAF sensor with dedicated MAF cleaner, then recheck trims; a clogged sensor element is a frequent and cheap fix
- Check fuel pressure at the rail with a gauge and compare against the manufacturer specification, both at idle and under a snap-throttle load
- Inspect for an exhaust leak ahead of the Bank 2 upstream O2 sensor and verify the sensor is switching correctly before condemning any parts
- Compare Bank 1 and Bank 2 trims side by side - a large gap between the two banks isolates the problem to Bank 2 hardware rather than a shared cause
How much does P0174 cost to fix on a Honda? (EUR)
Estimated repair costs for P0174 in EUR, compiled across makes. Honda parts and labour usually land towards the lower end of each range.
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Fix vacuum leak (replace hose or gasket) | €5–€60 | €60–€200 | €65–€260 | Moderate |
| Clean or replace MAF sensor | €10–€200 | €20–€60 | €30–€260 | Easy |
| Replace PCV valve | €10–€80 | €30–€120 | €40–€200 | Easy |
| Replace fuel pump | €100–€400 | €100–€300 | €200–€700 | Professional |
| Clean fuel injectors | €15–€50 | €50–€150 | €65–€200 | Moderate |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
Codes related to P0174
These codes are often seen alongside P0174 or point to related issues, on any make:
Looking for the full P0174 reference (all makes, full diagnosis flow, complete repair cost matrix)? See the main P0174 guide