The Quick Answer above is the generic definition. What follows is the model-specific detail for the Porsche models that log P0155.
DTC/P0155·Porsche
P0155 on Porsche: Causes, Symptoms and Fix Cost
Quick Answer
Low SeveritySafe to drive (short-term)Porsche
P0155 on a Porsche means the internal heater of the upstream oxygen sensor on bank 2 has failed or lost its power or ground, so the sensor takes longer to reach working temperature after a cold start. Bank 2 is the half of a V6, V8 or flat-six engine that does not contain cylinder 1 (a few inline-sixes with a split exhaust, such as BMW's M54, also have one). It is the same fault as P0135 on the other bank. The usual cause is a burned-out heater inside the sensor, though a blown fuse or damaged wiring can do the same.
Typical repair cost, all makes€1 - €320
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Porsche Boxster (986)
1996-2004The 986 Boxster's flat-six has four oxygen sensors: one before and one after the catalytic converter for bank 1 (cylinders 1-3) and the same pair for bank 2 (cylinders 4-6). All four are listed as the same part and fully interchangeable on this car, so swapping the two pre-cat sensors is a free test: if the heater code changes to P0135, the sensor's heater has failed; if P0155 stays, check for battery voltage on the heater pins of the bank 2 harness plug.
What causes P0155 on a Porsche?
Beyond the generic causes listed on the main P0155 page, these are the patterns noted for Porsche models:
Porsche Boxster (986)Burned-out heater in the bank 2 (cylinders 4-6) pre-cat sensor
Porsche Boxster (986)Loss of heater supply voltage at the bank 2 harness plug
How to diagnose P0155 on a Porsche with OBD2
Follow these steps to pinpoint the root cause of P0155:
- Read all stored codes. If other heater codes (P0135, P0141, P0161) are stored too, suspect a shared fuse, relay or wiring fault rather than one sensor
- Check the O2 sensor heater fuse and replace it if blown, then find out why it blew before condemning the sensor
- Unplug the bank 2 upstream sensor and measure resistance across its two heater pins. A healthy heater usually reads a few ohms; check the specification for your engine. An open circuit means the heater has burned out
- With the key on, back-probe the harness plug and confirm battery voltage on the heater supply wire. No voltage points to a fuse, relay or wiring fault upstream of the sensor
- Inspect the connector and the wiring run for corrosion, melted insulation and chafing against the exhaust
- Replace the sensor if the heater reads open or out of range, clear the code and confirm it stays off after a cold start and warm-up
How much does P0155 cost to fix on a Porsche? (EUR)
Estimated repair costs for P0155 in EUR, compiled across makes. Expect Porsche 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 P0155
These codes are often seen alongside P0155 or point to related issues, on any make:
Looking for the full P0155 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0155 guideSkanyx · Porsche
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