The Quick Answer above is the generic definition. What follows is the model-specific detail for the Mercedes-Benz models that log P0173.
DTC/P0173·Mercedes-Benz
P0173 on Mercedes-Benz: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeveritySafe to drive (short-term)Mercedes-Benz
P0173 on a Mercedes-Benz means the ECU has pushed long-term fuel trim on Bank 2 to the limit of its correction range and still cannot maintain the target air-fuel ratio. Because P0173 only affects one bank, it usually points to something specific to Bank 2 (a leak, a degraded sensor, or a dirty injector on that bank) rather than a whole-engine issue like a clogged fuel filter that would affect both banks.
Typical repair cost, all makes€70 - €420
Connect any standard Bluetooth OBD2 adapter to your Mercedes-Benz and Skanyx tells you what P0173 means on that engine, whether it is safe to keep driving, and what the fix should cost. Free on iPhone and Android.
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Mercedes E-Class
2011-2024On the W212 E-Class with the M276 V6, check the Bank 2 upstream lambda sensor and look for air leaks at the intake manifold seals on that side. Intake manifold work is labour-intensive because of access, even when the parts themselves are inexpensive.
What causes P0173 on a Mercedes-Benz?
Beyond the generic causes listed on the main P0173 page, these are the patterns noted for Mercedes-Benz models:
Mercedes E-ClassAir leak at the intake manifold seals on the bank 2 side of the M276
Mercedes E-ClassBank 2 lambda sensor slow response after heat soak
How to diagnose P0173 on a Mercedes-Benz with OBD2
Follow these steps to pinpoint the root cause of P0173:
- Read live data: focus on short-term and long-term fuel trim for Bank 2. A long-term trim above +20% or below -20% confirms the bank has been hitting its limits
- Compare Bank 2 trims to Bank 1. If only Bank 2 is out of range, the cause is bank-specific (one injector, one sensor, one manifold gasket section)
- Smoke-test the intake on Bank 2 specifically. On V engines, intake manifold gaskets fail one side at a time as plastic shrinks unevenly
- Swap the upstream sensors between banks and re-check live data. If the high trim follows the sensor, replace it; if it stays on the original bank, focus on mechanical causes
- Inspect for exhaust leaks ahead of the Bank 2 upstream sensor. A small leak can pull fresh air into the exhaust stream and trick the sensor into reading lean
How much does P0173 cost to fix on a Mercedes-Benz? (EUR)
Estimated repair costs for P0173 in EUR, compiled across makes. Expect Mercedes-Benz parts and labour towards the upper end of each range.
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
Codes related to P0173
These codes are often seen alongside P0173 or point to related issues, on any make:
Looking for the full P0173 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0173 guideSkanyx · Mercedes-Benz
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