P0155 on Cadillac: Symptoms, Causes & Fix
Official technical diagnostic wire for fault code P0155 specifically affecting Cadillac vehicles (Escalade, Escalade-V, CT5, CT5-V Blackwing, CT4).
Select Your Cadillac Model for P0155:
1. Common Symptoms on Cadillac Vehicles
When Cadillac Engine Control Modules (ECM) trigger fault code P0155, drivers typically report:
2. Root Causes on Cadillac Engines
Historical diagnostic claims across Cadillac engines point to the following failure distribution:
3. Step-by-Step Fix Protocol for Cadillac
Inspect the O2 HTR fuse in the engine fuse box with a test light or multimeter. on Cadillac engines.
Unplug the sensor connector and measure resistance between the two heater pins. An open circuit (infinite ohms / OL) confirms a dead internal heater. on Cadillac engines.
Remove faulty sensor and install a new OEM oxygen sensor with built-in heater. on Cadillac engines.
Clear DTCs and allow engine to cool down, then restart to confirm P0155 does not return. on Cadillac engines.
Equipment for Diagnosing Cadillac (P0155)
Cadillac OEM Replacement Sensor
Direct-fit replacement assembly engineered to OEM tolerances for Cadillac.
AstroAI Auto-Ranging Digital Multimeter
Essential for testing 0.1V–5.0V sensor reference signals, ground continuity (<0.20Ω), and harness resistance.
BlueDriver Bluetooth Pro OBDII Scan Tool
Reads and clears enhanced codes (ABS, Airbag, Transmission, Engine) & live freeze-frame telemetry on phone.
4. Cadillac P0155 Frequently Asked Questions
What does code P0155 mean on a Cadillac?
On Cadillac vehicles, P0155 indicates that the Engine Control Module (ECM) detected o2 sensor heater circuit malfunction (bank 2 sensor 1). This typically points to Burnt-out heating element inside the Bank 2 Sensor 1 O2 sensor or Blown O2 heater fuse in under-hood fuse block.
Can I continue driving my Cadillac with code P0155?
Yes. The sensor will take longer to warm up, causing brief open-loop fuel delay on cold starts. Because this code carries a Medium severity rating on Cadillac powertrains, we recommend scanning live data values promptly to prevent secondary damage.
How much does it cost to fix code P0155 on a Cadillac?
Estimated DIY parts cost ranges from $120 - $350 (DIY: $45 - $120), while professional shop repairs at an authorized Cadillac dealership or independent specialist typically range from $180 to $380 including diagnostic labor.