P0135 on 2015-2022 Chevrolet Colorado 2.5L: O2 Sensor Heater Causes and Fixes

What's Unique About the 2015-2022 Chevrolet Colorado

On the Chevrolet Colorado with the 2.5L LCV engine, the P0135 code is a very common and straightforward issue. Because the four-cylinder engine has a single exhaust bank, "Bank 1" is the only bank, and "Sensor 1" is the easily accessible upstream sensor on the exhaust manifold. The failure is almost always internal to the sensor itself, making for a confident diagnosis. While wiring issues are possible, owner experiences overwhelmingly point to the sensor's heating element simply wearing out from thousands of heat cycles.

Symptoms You May Notice

• Check Engine Light is on
• Reduced fuel economy
• Rough idling or poor performance, especially during cold starts.
• Failing a vehicle emissions test.
• Bad smell from exhaust or black smoke during warm-up.

Most Likely Causes

1. Failed Upstream (Bank 1, Sensor 1) Oxygen Sensor 🔴 High Probability → Shop Oxygen Sensor The internal heater element is a common wear-and-tear component that is subjected to thousands of heat cycles and eventually burns out. This is the most frequent cause of P0135 on this platform.
   How to confirm: Disconnect the sensor and measure the resistance between the two heater circuit pins (usually the two same-colored wires, often black) on the sensor's connector. A good sensor will have a low resistance, typically between 3-10 ohms. A real-world test on a new sensor showed 6 ohms, while the failed sensor read 227 ohms. A reading of infinity/OL (open circuit) or a very high resistance confirms the heater element has failed.
   Typical fix: Replace the Bank 1, Sensor 1 oxygen sensor located on the exhaust manifold. A 22mm (or 7/8") slotted oxygen sensor socket is required for removal and installation.
   Est. part cost: $45-$90
2. Blown O2 Sensor Heater Fuse ⚪ Low Probability → Shop Oxygen Sensor
   How to confirm: Check fuse F47 (a 15A mini fuse labeled 'O2 HTR 1') in the under-hood fuse box to ensure it is not blown. If it is, suspect a short in the wiring or the sensor itself.
   Typical fix: Replace the fuse after inspecting the wiring and sensor for shorts. Do not simply replace the fuse without checking for the underlying cause, as it will likely blow again.
   Est. part cost: $1-$5

Rare But Worth Checking

• Damaged Wiring or Connector: The O2 sensor wiring harness is routed near hot exhaust components and can chafe or melt. GM issued TSB 18-NA-307 regarding the engine harness potentially chafing against the camshaft cover or cylinder head, which could cause a short or open circuit in various systems, including the O2 sensor heater. Always inspect the wiring visually before replacing parts.
• Faulty Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is extremely rare. The driver circuit within the ECM that controls the O2 sensor heater can fail. This should only be considered after all other possibilities (sensor, fuse, wiring) have been definitively ruled out by a professional.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0135 is present.
2. Locate the Bank 1, Sensor 1 O2 sensor. On the 2.5L engine, it is on the passenger side, screwed into the exhaust manifold before the catalytic converter.
🎬 Watch: Step-by-step guide to replacing your upstream oxygen sensors.
3. Visually inspect the wiring harness and connector going to the sensor for any signs of melting, chafing, or corrosion. Pay close attention to where the harness passes near the camshaft cover, as noted in TSB 18-NA-307.
4. Check fuse F47 (15A) in the under-hood fuse box to ensure it is not blown.
5. Disconnect the O2 sensor's electrical connector.
6. Using a multimeter set to Ohms (Ω), measure the resistance between the two same-colored (usually black) wires on the SENSOR side of the connector.
7. A good sensor should have a low resistance, typically between 3-10 ohms. A reading of infinity/OL (open circuit) or a very high resistance (e.g., over 200 ohms) confirms the heater element has failed.
8. If the sensor resistance is good, check for power at the HARNESS side of the connector. With the ignition on (engine off), use a multimeter to verify that battery voltage (~12V) is present at the heater power pin. On the 2.5L, this is typically the second pin from the end when the connector's white tab is facing you.
9. If the sensor tests bad, replace it. If the sensor tests good but there is no power at the harness, the problem is in the vehicle's wiring or the ECM.

Parts You'll Likely Need

• Upstream Oxygen Sensor (Bank 1, Sensor 1) (OEM #12643707) — This is the most common failure point for code P0135. The internal heating element wears out over time.
  Trusted brands: ACDelco (GM Original Equipment) #12643707, Denso #234-8080, Bosch, Walker
  OEM price range: $45-$70
  Aftermarket price range: $50-$90

Related Codes That Often Appear With This One

• P0030 — This is a more generic code for the HO2S Heater Control Circuit for Bank 1 Sensor 1. They often appear together as they both point to a fault in the same heater circuit.
• P0031 — This code for 'HO2S Heater Control Circuit Low' can also appear with P0135, indicating a low voltage condition in the same heater circuit.
• P0132 — This code for 'O2 Sensor Circuit High Voltage' can sometimes appear with P0135 if the heater failure also impacts the sensor's signal output, indicating a more comprehensive internal failure of the sensor.

Technical Service Bulletins (TSBs) & Recalls

• 18-NA-307: Potential for engine wiring harness to chafe against engine components, causing shorts.
• PIP5529B: Discusses multiple DTCs (including P0171, P0131, P0137) that can be caused by loose intake manifold bolts on the 2.5L LCV engine.

Platform-Specific Known Issues

• TSB 18-NA-307: Engine Harness Chafing: This bulletin notes that the engine wiring harness can chafe against the camshaft cover or cylinder head. This can cause a short or open in various circuits, including those for camshaft position sensors (P0365, P0366) and potentially the O2 sensor heater, making a wiring inspection important.
• TSB PIP5529B: Loose Intake Manifold Bolts: While not a direct cause for an isolated P0135, this TSB notes that loose intake manifold bolts on the 2.5L engine can cause vacuum leaks, leading to a variety of O2 sensor and air/fuel mixture codes like P0171 (System Too Lean), P0131, and P0137. This is worth noting if P0135 appears with other lean or sensor range codes. The fix involves re-torquing the bolts with threadlocker.
• Real Owner Experience: A 2018 GMC Canyon 2.5L owner experienced severe stumbling and near-stalling with codes P0030, P0031, P0132, and P0135. A multimeter test on the original sensor's heater circuit showed 227 ohms. Replacing the sensor with a new ACDelco unit (which tested at 6 ohms before installation) resolved all issues.

Mechanic-Grade Diagnostic Values

• O2 Sensor Heater Circuit Resistance — expected: 3 - 10 Ohms at room temperature. A new ACDelco sensor often measures around 6 Ohms.. Failure: A reading of infinity/OL (Open Loop) or very high resistance (e.g., >200 Ohms) indicates a failed heater element.
• O2 Sensor Heater Circuit Voltage Supply — expected: ~12V (Battery Voltage) with Key On, Engine Off.. Failure: 0V or significantly low voltage at the heater power supply pin on the harness connector indicates a problem with the fuse, relay, or wiring, not the sensor.
• O2 Sensor Heater Circuit Current Draw — expected: 0.5 - 2.0 Amps when active.. Failure: Current draw that is higher or lower than the specified range indicates a fault in the heater or circuit.
• Mode 6, Test ID $81 — expected: A 'Pass' status.. Failure: A 'Fail' status for this monitor ID on a Mode 6 capable scan tool confirms the heater circuit test is what triggered the P0135 code.

Wiring & Ground Locations

• HO2S B1S1 Connector — On the passenger side of the engine, connecting the upstream O2 sensor to the main engine harness.. This is the primary test point. The two same-colored wires (usually black) are for the heater circuit. With the connector's white locking tab facing you, Pin 1 is the heater ground and Pin 2 is the 12V power supply from the fuse.
• G103 — Typically found on the lower left (driver's) side of the engine block.. This is a primary engine block ground point. The ECM and its sensors, including the O2 sensor heater circuit, rely on a clean engine-to-chassis ground. A corroded or loose ground at G103 can cause intermittent and difficult-to-diagnose electrical faults across multiple systems.

Real Owner Repair Stories

• YouTube channel 'Doing Dave Stuff' (2018 GMC Canyon 2.5L I4) — Severe engine stumbling, near-stalling, and multiple Check Engine Light codes (P0030, P0031, P0132, P0135).
  ❌ Tried (didn't work) Initial diagnosis was confusing due to the number of codes.
  ✅ What actually fixed it The upstream O2 sensor's heater had failed. The old sensor measured 227 Ohms. Replacing it with a new OEM ACDelco sensor (P/N 12643707), which measured 6 Ohms before installation, resolved all codes and driveability issues.
• Go-Parts Repair Database citing a YouTube video (2018 GMC Canyon 2.5L I4) — Engine stumbling, stalling, and multiple heater circuit codes including P0135.
  ❌ Tried (didn't work) The owner was initially confused as the O2 sensor had been replaced only one year prior.
  ✅ What actually fixed it The one-year-old aftermarket sensor (Walker brand) had failed prematurely. Its heater resistance measured 227 Ohms. Replacing the failed aftermarket part with a new OEM ACDelco sensor fixed the problem, highlighting the potential for poor quality in non-OEM sensors.
• NHTSA ODI #11632222 — An owner reported a "Reduced Propulsion" message on the dash along with P0135 and several other codes. A technician found a blown fuse (F03) for the EGR valve, suggesting that a stuck EGR valve could potentially impact shared circuits.
• NHTSA ODI #10156207 — A driver noted that a computer check revealed P0135 along with codes P1189 and C1216. Although the dealer initially tested the items per the trouble tree and found them good, the warning lights returned the following day.

When the Usual Fixes Don't Work

• If the F47 (or 'Misc 2') fuse blows repeatedly, do not continue to replace the O2 sensor. This indicates a persistent short to ground in the wiring harness. The most likely location for this short is where the harness may have chafed against the engine, as described in TSB 18-NA-307. A thorough inspection of the harness path is required before further part replacement.

OEM Part Supersession History

• 12643707 → 12686342 (ACDelco 213-4764) — Standard part evolution and potential supplier changes.
  Heads up: While 12643707 is still widely sold and confirmed to work on models up to 2018, some databases suggest 12686342 is the newest number. Always verify the correct part number with a VIN at a GM dealer to ensure compatibility, as running changes can occur.

Model Year Variations Within This Range

• 2018 and potentially newer: While fuse F47 (15A) is the commonly cited fuse for the O2 heater, some 2018 models may have the circuit powered by a 10A 'Misc 2' fuse that is shared with other components like the EVAP purge solenoid and thermostat heater. This changes the diagnostic path if multiple specific codes are present.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• 8-Speed Automatic Transmission Shudder (V6 Models) 🟠 Medium — Very common on 2017-2019 V6 models. Feels like driving over rumble strips at light throttle between 25-80 mph. (Ref: TSB 18-NA-355. The fix involves a specialized fluid flush procedure to replace the original factory fluid with a new formulation of Mobil 1 Synthetic LV ATF HP.)
• Thermostat Failure / Cooling System Issues 🟠 Medium — Owners report intermittent overheating, temperature gauge fluctuations, or the engine failing to reach operating temperature. This can be caused by a stuck thermostat or air in the cooling system.
• Frame Wax Coating Peeling / Corrosion 🟡 Low — Affects some full-size GM trucks and SUVs, but the Colorado uses a painted frame, not a wax coating, making this less of a direct issue for this specific model, though frame rust is still a concern in salt-belt regions. (Ref: TSB 19-NA-255 addresses this for other GM trucks by removing the wax and applying a new coating.)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: Almost never for this repair. A used part may be considered for a damaged wiring harness connector pigtail if a new one is unavailable, but the sensor itself should always be new.

What to inspect on the donor part:

• For a connector pigtail: ensure plastic is not brittle, locking tabs are intact, and there is no corrosion on the pins.

OEM-only on this vehicle (don't cheap out):

• Oxygen Sensor: While not strictly 'OEM-only', using an OEM (ACDelco) or original supplier (Denso) sensor is very strongly recommended. Aftermarket sensors have a documented history of premature failure on this platform.

Aftermarket brands forum-validated for this vehicle:

• Denso: Widely reported to be the original manufacturer for ACDelco sensors.
• NTK/NGK: Generally considered a high-quality alternative with good performance on GM vehicles.

Brands owners have reported issues with on this vehicle:

• Unbranded sensors from online marketplaces (Amazon, eBay).
• Walker: One specific repair story documents a Walker sensor failing within one year.
• Bosch: Some forum discussions suggest avoiding Bosch sensors for this specific GM application, citing potential incompatibility.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0030 — HO2S Heater Control Circuit (Bank 1, Sensor 1); often appears alongside P0135 when the heater circuit fails.
• P0031 — HO2S Heater Control Circuit Low (Bank 1, Sensor 1); a companion code indicating a fault in the same heater circuit.
• P0131 — O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1); noted in TSB PIP5529B as a potential related code on the 2.5L engine.
• P0132 — O2 Sensor Circuit High Voltage (Bank 1, Sensor 1); can occur simultaneously with heater circuit failures.
• P0137 — O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2); mentioned in TSB PIP5529B as a code that can appear due to intake manifold vacuum leaks.
• P0171 — System Too Lean (Bank 1); can be triggered by vacuum leaks from loose intake manifold bolts as described in TSB PIP5529B.
• P0365 — Camshaft Position Sensor B Circuit (Bank 1); identified in TSB 18-NA-307 as a code that may appear due to the same engine harness chafing that affects O2 sensor circuits.

Frequently Asked Questions