P0155 Code: Jeep Cherokee (2019-2023) - Causes, Symptoms & Fixes

P0155 Diagnostic Guide for 2019–2023 Jeep Cherokee (OBD-II)

Recalls

• No recalls found in NHTSA database

Important note on data

• The provided NHTSA data shows no owner complaints for this exact issue with this model year range, and no recalls. That limits code-specific symptom statistics and documented fixes. The guide below combines the P0155 definition with typical industry diagnostic practices and 2025 pricing estimates for reference. Always verify with your own vehicle’s data and local shop rates.

CODE MEANING AND SEVERITY

-Code: P0155
-Full name: O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
-What it means: The heater element inside the upstream oxygen sensor on Bank 2 (Sensor 1) is not heating properly. Heated O2 sensors warm up faster to operating temperature, which helps the PCM get accurate readings sooner. A heater fault can cause delayed response, incorrect fuel trim adjustments, and potential emissions issues.
-Severity on a Jeep Cherokee (2019–2023): Moderate. The MIL (check engine light) will typically illuminate, and the vehicle may fail an emissions test or experience degraded fuel economy and drivability if the sensor readings stay slow to heat and the PCM relies on degraded data. The problem may not immediately affect performance, but long-term driving with a non-heating sensor can increase emission outputs and cause diagnostic trouble codes to cascade to other systems.

COMMON CAUSES ON JEEP CHEROKEE

• Faulty Bank 2 Sensor 1 O2 sensor (bad heater element)
• Damaged or corroded wiring harness to Bank 2 Sensor 1 heater circuit
• Faulty or blown fuse/relay supplying power to the O2 heater circuit
• Poor or intermittent electrical connection at the sensor connector
• Short to 12V or open circuit in the heater wiring
• Ground issue affecting the heater circuit
• PCM/ECU glitch (less common, but possible)
• Exhaust leaks or exhaust system issues near the sensor (can affect readings, though not the heater circuit itself)
• Contamination or misinstallation of the bank 2 upstream sensor (e.g., wrong sensor, incorrect position, or damaged sensor body)

SYMPTOMS

• Check Engine Light (MIL) on or intermittently illuminated
• Decreased or inconsistent fuel economy
• Potentially rough idle or slight hesitation, though not always evident
• No obvious drivability faults in many cases; vehicle may run normally but with emissions concerns
• Possible failure of an emission test/inspection due to poor sensor heating
• In some cases, there may be no noticeable symptoms beyond the MIL and a P0155 code on scan

DIAGNOSTIC STEPS

Tools you may need:

• OBD-II scanner with live data and DTC read/erase capability
• Multimeter/ohmmeter
• Basic hand tools (screwdrivers, pliers, socket set)
• Safety equipment (gloves, eye protection)

Step-by-step guide

Confirm the code and data

• Retrieve P0155 with a quality scan tool.
• Note freeze-frame data: engine temperature, RPM, whether the fault occurs at startup or after warm-up.
• Check for other related codes (e.g., P013X, P016X family indicating other O2 sensor issues).

Inspect obvious wiring and connector condition

• Visually inspect the Bank 2 Sensor 1 upstream O2 sensor and its wiring harness.
• Look for damaged insulation, exposed wires, signs of chafing, heat damage, or corrosion at the sensor connector.
• Disconnect and reconnect the sensor harness to ensure a solid connection.

Check fuses, relays, and power supply

• Identify the fuse/relay that powers the O2 sensor heater circuit (per the Cherokee’s fuse box diagram or service manual).
• Check fuse integrity and inspect relay operation if applicable.
• With the ignition on (or engine running if safe), check for ~12V supply to the heater circuit at the sensor harness connector when the PCM enables the heater. Use a multimeter or a scan tool to verify heater power activity.

Test the heater circuit for continuity and shorts

• Disconnect the sensor connector.
• Use the multimeter to:
  • Check resistance across the heater terminals on the sensor itself (compare to OEM spec if available; a typical heater circuit is designed to have a low resistance, indicating a good heater; an open or near-open reading indicates a bad sensor).
  • Check for continuity from the heater terminal to the vehicle ground and to the PCM power feed. Look for unintended shorts to power (12V) or to ground.
• If the heater shows open circuit or a short, replace the sensor.

Check sensor grounding and chassis grounds

• Ensure the sensor’s body is properly grounded via its mounting hardware and/or the wiring harness ground.

Rule out exhaust-related issues

• Inspect for exhaust leaks upstream of Bank 2 Sensor 1, which can cause erroneous sensor readings. While this doesn’t fix a heater fault, it confirms whether a sensor reading issue might be stemming from external conditions.

Perform a functional test

• If your scanner provides live data, monitor Bank 2 Sensor 1 readings and the heater current/voltage when the engine warms up.
• If the heater current is absent or inconsistent after the above checks, plan for sensor replacement.

Confirm fix

• After repairs, clear codes and drive the vehicle under typical conditions (short trips plus a longer highway run) to ensure the MIL does not return.
• Re-scan for codes to confirm the P0155 does not reappear and that sensor data reports normally.

Additional notes

• If multiple O2 sensor heater codes appear (e.g., for Bank 1 Sensor 2 or Bank 2 Sensor 2), address per the diagnostic plan for the affected sensor(s).
• If the sensor has been replaced and the code returns, investigate PCM wiring or a possible misdiagnosis (consider professional assistance).

RELATED CODES

• O2 sensor-related heater and circuit codes (general family)
  • P0130 to P0134: Upstream O2 sensor circuit faults (Bank 1)
  • P0135 to P0138: O2 sensor heater circuit faults (Bank 1)
  • P0139: O2 sensor heater circuit fault (Bank 1)
  • P0150 to P0154: O2 sensor circuit faults (Bank 2; upstream sensors)
  • P0156 to P0159: O2 sensor heater circuit faults (Bank 2)
  • P0160 to P0164: O2 sensor circuit faults (Bank 2; downstream sensors)
• Note: These are commonly referenced categories for O2 sensor-related problems and are often seen alongside P0155 when diagnosing emissions and heater issues.

REPAIR OPTIONS AND COSTS (2025 prices)

Prices are approximate and can vary by region, dealer vs. aftermarket parts, and whether labor is done by a dealer or independent shop.

• Bank 2 Sensor 1 O2 sensor (replacement sensor)
  • Aftermarket part: about $25–$120
  • OEM/Dealer part: about $120–$260
• Labor to replace Bank 2 Sensor 1 O2 sensor
  • Time: roughly 0.5–1.0 hour (some vehicles may require more time if access is tight)
  • Labor rate: $80–$180 per hour depending on region and shop
  • Estimated total: $100–$350 (parts plus labor)
• Wiring harness repair or connector replacement (if wiring/connector is at fault)
  • Parts: $10–$60 (pins, connectors, sealing)
  • Labor: $50–$150
  • Estimated total: $60–$210
• Fuse/relay replacement (if the issue is power supply related)
  • Parts: a couple dollars to tens of dollars
  • Labor: minimal (if done by DIY)
• PCM/ECU repair or replacement (rare)
  • Parts: $400–$1,000 (depending on OEM vs. rebuilt)
  • Labor: variable (install and programming)
  • Overall: often avoided unless PCM is proven faulty
• Summary ranges (typical case of just replacing the sensor and related intermittent wiring issue)
  • Parts: $25–$260
  • Labor: $50–$180
  • Total range: roughly $75–$440

DIY vs PROFESSIONAL

• DIY feasibility: Replacing an upstream O2 sensor is a common and manageable repair for DIY enthusiasts. It usually involves identifying the sensor, disconnecting the connector, unscrewing the sensor from the exhaust, applying anti-seize when reassembling (if the sensor is designed for it), and reinstalling the new sensor. Safety note: engine and exhaust components can be extremely hot; wear gloves and let the exhaust cool.
• When to bring to a professional:
  • If you find damaged wiring or a corroded connector that requires electrical repair.
  • If you don’t have proper tools (torque wrench, O2 sensor socket) or if you’re uncomfortable tracing wiring and diagnosing heater circuits with a multimeter.
  • If the code reappears after sensor replacement, indicating a potential PCM issue or wiring fault that requires more in-depth diagnostics.
• Pros of DIY: Lower upfront cost, learning experience, quick fix if you catch a faulty sensor early.
• Cons of DIY: Potential for cross-threading, improper torque on exhaust hardware, missed electrical faults, and voiding warranty if you’re under coverage.

PREVENTION

• Use quality oxygen sensors and avoid cheap, non-OEM sensors if possible, especially for critical emissions components.
• Regular maintenance: replace air filters, fuel filters (if applicable), and spark plugs as recommended; clean sensors and connectors as needed.
• Inspect wiring harnesses and connectors during routine maintenance to catch signs of wear, corrosion, or moisture ingress early.
• Avoid repeated short trips that prevent the catalyst and sensors from reaching operating temperature, which can stress sensor electronics over time.
• Address exhaust leaks promptly; leaks before the upstream sensor can corrupt sensor readings and diagnostics.
• When encountering irregular sensor data, resolve root causes promptly to prevent cascading codes and potential catalyst damage.

Data limitations

• Based on the provided NHTSA data, there are no listed owner complaints or recalls for this exact issue on 2019–2023 Jeep Cherokee. This means there is limited model-year–specific statistical context for P0155 within the dataset you provided. The diagnostic steps, causes, and repair guidance above reflect general OBD-II practice for P0155 and typical Jeep Cherokee architecture. If newer data becomes available, revisit the guide to incorporate any model-specific quirks or known service bulletins.