P0155 Code: Chevrolet Silverado (2019-2024) - Causes, Symptoms & Fixes

P0155 DIAGNOSTIC GUIDE for 2019-2024 CHEVROLET SILVERADO

Data snapshot from the provided NHTSA-era data:

• Complaints: No NHTSA owner complaints found for this make/model/year/issue combination.
• Recalls: No recalls found in NHTSA database for this make/model/year.
• If you’re diagnosing P0155, treat this guide as focused on general OBD-II procedure plus Silverado specifics, but note that the dataset shows no documented recalls or complaints tied to this code for these models.

CODE MEANING AND SEVERITY

• Code: P0155
• Full name: O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
• What it means on a Silverado: The upstream oxygen sensor on Bank 2 (the sensor before the catalytic converter on the second exhaust bank) is not heating properly. The heater element is used to bring the sensor up to its operating temperature quickly for accurate readings. A heater fault can prevent the sensor from reaching its optimal temperature, leading to delayed or erroneous oxygen sensor readings and downstream fuel trims.
• Severity and impact:
  • MIL/Check Engine Light: Likely illuminated.
  • Drivability: Often minimal immediate drivability impact, but can cause degraded fuel economy and higher emissions until repaired.
  • Emissions readiness: May affect readiness tests; depending on other faults, the PCM may store additional fault codes or flag related sensors.
• Important note: No recalls found in the provided data for this code on 2019-2024 Silverado, and there are no documented complaints in the given dataset. This means there isn’t an explicitly known factory defect noted here; still, the diagnostic approach below applies to typical P0155 symptoms.

COMMON CAUSES ON CHEVROLET SILVERADO

• Faulty upstream O2 sensor (Bank 2 Sensor 1) heater element
• Damaged, frayed, or corroded wiring harness or connector to Bank 2 Sensor 1 heater circuit
• Short to ground or short to power in the wiring for the heater circuit
• Blown fuse or bad PCM output controlling the heater circuit
• Poor connection or corrosion at the Sensor 1 Bank 2 sensor connector
• Exhaust leaks upstream of the sensor (can affect readings and complicate diagnosis, even if the heater circuit itself is the fault)
• Sensor replacement not addressing the root cause (e.g., a misdiagnosed wiring fault)

SYMPTOMS

• Check Engine Light illuminated with P0155 stored or pending
• Slightly degraded fuel economy or irregular fuel trims once the MIL is present
• No obvious drivability problem in some cases; in others, the engine may run a bit rough if other sensors compensate poorly
• Possible related codes seen alongside P0155 (common pairing): P0130–P0135 (Bank 1 Sensor 1/2 and Bank 2 equivalents) if misreads exist, or generic O2/Sensor circuit codes
• In some vehicles, a slow or absent O2 sensor heater can cause the sensor to struggle to reach operating temperature, which delays proper feedback to the PCM

DIAGNOSTIC STEPS

Preparation:

• Use a reliable OBD-II scanner that can read live data and freeze frames. Note the freeze-frame data, including engine RPM, load, vehicle speed, engine coolant temp, catalytic convert temps (if available), and any other sensor readings.
• Check for any related codes (P013x, P014x, P016x) that might indicate a broader O2 sensor issue or misfire history.
• Visually inspect around Bank 2 Sensor 1 (upstream sensor on the second bank) for wiring and connector condition, heat shield contact, and proximity to exhaust components.

Step-by-step:

Verify and document the code with scan tool data (confirm P0155 is the active code and note any related codes).

Visual inspection:

• Inspect Bank 2 Sensor 1 wiring harness and connector for cracks, frayed insulation, corrosion, bent pins, or water intrusion.
• Check for signs of exhaust heat damage near the sensor, melted insulation, or physical damage to the sensor housing.

Inspect fuses and power/ground:

• Identify the O2 sensor heater fuse(s) in the vehicle's fuse box (owner’s manual or service manual for exact locations). Confirm fuse integrity.
• Check for proper battery voltage and ground at the PCM; a fault in the heater drive circuit can be PCM-related, though this is less common.

Resistance test of the heater circuit:

• With the sensor removed (careful not to damage it), measure the resistance across the O2 heater pins (usually two heater pins). Typical sensor heater resistance is in the low ohm range (often single-digit to tens of ohms, depending on sensor model). If the resistance is open or significantly out of spec per the OEM spec, the heater element is faulty.
• If you cannot access OEM specs easily, a suspect heater short or open circuit is often diagnosed by resistance that is either very high (open) or very low (short).

Live data heater status test (if your scan tool supports it):

• With ignition on, check whether the heater is commanded ON by the PCM and whether it shows current draw when heated. Some tools display “Heater Circuit ON” or show current in amps; absence of heater current when commanded can indicate wiring, fuse, PCM, or sensor fault.

Sensor comparison test (isolation method):

• If feasible and you have a known-good sensor (or you can borrow from Bank 1 Sensor 1 for a short test, recognizing sensor tolerance differences), temporarily swap Bank 1 Sensor 1 with Bank 2 Sensor 1 to see if the code moves or clears. This is a diagnostic shortcut and not always recommended due to bank-specific calibration, but some technicians use cautious cross-testing to localize a sensor vs. wiring/PCM fault.

Exhaust leak check:

• Use smoke testing or a listening/feel method to identify any exhaust leaks upstream of Bank 2 Sensor 1 which could affect sensor readings and misdirect diagnostics.

If the heater circuit and wiring appear sound and no other faults found:

• Replace Bank 2 Sensor 1 O2 sensor (upstream, Bank 2) with a quality sensor recommended for your engine. After replacement, clear codes and run the vehicle to recheck for P0155.

Post-repair verification:

• Clear codes and drive under normal conditions. Monitor live data to confirm Bank 2 Sensor 1 readings heat up, reach expected operating temperature, and show responsive changes with fuel trims. Confirm that the heater circuit shows evidence of operation in live data after engine warming.

If codes persist after sensor replacement:

• Recheck wiring harness and connectors again.
• Reassess fuse/PCM status.
• Consider PCM-related diagnostics if other heater circuits fail (less common, typically reserved for advanced diagnostics).

RELATED CODES

• P0150 – P0154: O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1) and related bank 2 sensor 1 codes
• P0130 – P0135: O2 Sensor Circuit Malfunction / Heater-related codes for Bank 1 Sensor 1, Bank 1 Sensor 2, Bank 2 Sensor 1, Bank 2 Sensor 2 (contextual with Bank 2 Sensor 1)
• P0160 – P0164: O2 sensor circuit fault codes on Bank 2 sensors (if your vehicle uses these variants in diagnostic trees)
• Other O2 sensor circuit faults (P013x/P015x family) that may appear in conjunction with P0155

REPAIR OPTIONS AND COSTS (2025 prices)

Notes:

• Prices shown are typical ballparks for parts and labor in many markets. Actual pricing will vary by region, dealer vs independent shop, and whether OEM or aftermarket sensors are used.

• If the root cause is wiring/harness or PCM, costs can vary widely and may involve more labor.

• Option A: Replace Bank 2 Sensor 1 O2 sensor (upstream)

  • Parts: $40–$140 (aftermarket) or $60–$180 (OEM/DELPCO/Denso equivalents may be higher)
  • Labor: about 0.4–1.0 hours
  • Typical total installed: $120–$260
  • Pros: Most common cure for heater circuit faults; straightforward replacement
  • Cons: If wiring is faulty, this will not fix the root cause

• Option B: Inspect/repair wiring harness and connectors (Bank 2 Sensor 1 heater circuit)

  • Parts: minor (connector repair, harness splices if needed)
  • Labor: 1.0–3.0 hours depending on access and damage
  • Typical total installed: $150–$450
  • Pros: Corrects root cause if harness/connector is damaged
  • Cons: Can be labor-intensive; sometimes wiring damage is hidden under harness sheathing

• Option C: Fuse/PCM-related fault resolution

  • Fuses: replacement cost is minor (parts <$20; labor minimal if located quickly)
  • PCM/ECU heater driver: if PCM output is faulty, comprehensive diagnosis required; potential replacement/rewrap programming
  • Typical total installed: $200–$1000+ if PCM repair or replacement is needed
  • Pros: Fixes electrical driver fault
  • Cons: Expensive and may require programming; less common

• Option D: Exhaust leak repair (as a supplementary check)

  • Parts: gaskets, clamps, hangers as needed
  • Labor: varies
  • Note: While not a direct fix for heater circuit, eliminating exhaust leaks can improve sensor performance and prevent misdiagnosis

• Summary guidance:

  • If the Bank 2 Sensor 1 heater circuit is confirmed faulty (heater resistance out of spec, heater not energizing as commanded, open/short found in wiring), replacing the sensor (Option A) is the most common and cost-effective route.
  • If wiring is damaged, repair the wiring harness (Option B) first or alongside sensor replacement.
  • Reserve PCM-related fixes for when sensor, wiring, and fuse checks are all clean and the heater circuit remains non-functional.

DIY vs PROFESSIONAL

• DIY feasibility:
  • Easy-ish job for someone with basic hand tools and access to a service manual or OEM guidance.
  • Pros: Lower upfront cost; quick sensor replacement if wiring is sound.
  • Cons: Wiring harness issues can be hidden; improper sensor replacement or failing to address PCM issues can lead to persistent codes.
• Professional approach:
  • Pros: Correct isolation of sensor vs wiring vs PCM faults; use of OEM-level diagnostic tools; proper torque and anti-seize guidance for sensor installation.
  • Cons: Higher labor rate; typical diagnostic steps may reveal non-obvious root causes.
• Safety notes for DIY:
  • Exhaust components can remain extremely hot; allow cooling.
  • Disconnect the battery when disconnecting electrical connectors if you’re working near the electrical harness.
  • Use proper PPE; avoid damaging sensor threads; use anti-seize or thread lubricant per sensor manufacturer guidance if applicable (check OEM recommendation).

PREVENTION

• Regular maintenance helps minimize O2 sensor-related issues:
  • Use high-quality fuel and keep intake and fuel systems clean with recommended cleaners if appropriate for your vehicle.
  • Replace upstream O2 sensors at OEM-recommended intervals or when symptoms arise to prevent cascading fuel trim issues.
  • Keep the exhaust system intact; fix any exhaust leaks promptly to prevent false readings.
  • Inspect the O2 sensor wiring harness and connectors for signs of wear, corrosion, or moisture intrusion during routine service (oil leaks near the sensor and heat cycling can degrade harnesses over time).
  • Avoid using aftermarket parts that compromise sensor performance; if you use aftermarket sensors, choose trusted brands with good compatibility for Silverado engines.
• Data limitation reminder:
  • The provided data shows no NHTSA complaints or recalls for these model years related to P0155, which limits statistical context. Use the diagnostic steps and cost estimates as practical guidance rather than as a reflection of a known nationwide trend.

Final notes

• P0155 on a 2019-2024 Silverado indicates a problem with the Bank 2 Sensor 1 O2 sensor heater circuit. Start with a visual inspection and fuse check, then test the sensor heater resistance and heater operation. Replacing the sensor is the most common fix if the heater circuit and wiring test faulty. If wiring is intact and the heater is still not functioning, consider PCM-related diagnostics as a last resort.