P0155: O2 Sensor Heater Circuit Bank 2 Sensor 1
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Yes - slightly worse economy during warm-up until fixed.
Symptoms
- Check engine light
- Marginal economy loss on short trips
Likely causes, most common first
- Bank 2 upstream sensor heater burned out
- Heater fuse blown
- Connector or wiring fault
Read P0155 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0155 is the heater circuit of the bank 2 front oxygen sensor - the V-engine mirror of P0135. Until exhaust heat warms the sensor naturally, fueling runs on estimates.
Check the fuse before the sensor; shared heater fuses are common and cost nearly nothing to rule out.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Owner reports mentioning P0155
“The Blazer is showing many codes in the ECM, even though it seems to be running properly. The codes include: p0171, p0174, p0101, p0128, p0155, p0300, p1870, p0128, p0155. The dash recently showed warning lights for parking brake, ABS, and Service Engine soon. It was checked a few days ago by a local repair shop. Two previous recalls showed multifunction switch failures which affected many vehicles.”2002 Chevrolet Blazer · Oct 2023
“Vehicle will not operate over 1,000 rpm. It had the throttle body cleaned on 15 aug 2013 under customer satisfaction recall 12n03. For the original complaint, the idling spiked where in this instance the car will not accelerate above 1,000 rpm. The codes associated with this incident are: p060b; p061b; p0122; p0155; p0222; p0316; p0480; p2104; p2110; p2122; p2127; p2132; p2135. *tr”2007 Ford Freestyle · Jan 2014 · 145,000 mi
“My 2001 toyota sequoia had an issue with "check engine" light at approximately 77,000 miles. It pulled the p0155 code that indicated failure of oxygen sensor. Toyota had at least two technical service bulletins on the issue showing this problem as widely known. What is more, on tundra vehicles (that have the same engine)toyota recognized the issue by extending the warranty on sensors and on that specific code up to 90000 miles. The repairs cost was almost $340, pulling the code (5 min) and replacing the sensor (15 min) was charged at 2 hrs of labor. Toyota customer service refused to cover repairs. Customer service case 2007-07250397. *tr”2001 Toyota Sequoia · Jul 2007 · 77,088 mi
Cars that report P0155 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0155?
Yes - slightly worse economy during warm-up until fixed.
How much does it cost to fix P0155?
Typical US repair costs range from $40 for the simplest fix (fuse or wiring) to $450 in the worst case. The right number depends on which cause your car has - see the causes list.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.