B0158 on 2010-2014 Buick LaCrosse: Outside Temp Sensor Causes and Fixes

What's Unique About the 2010-2014 Buick LACROSSE

For the second-generation LaCrosse (2010-2016), the ambient air temperature sensor is located in the front of the vehicle, making it vulnerable to damage from road debris, moisture, and minor impacts. Service manual diagrams for the 2011 LaCrosse pinpoint its location behind the grille, clipped into the front of the engine compartment, making it a common failure point. This prompted General Motors to issue Technical Service Bulletin (TSB) #PIC5656F, which guides technicians to check the sensor's connection and wiring as the first diagnostic step for a B0158 code.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• The outside temperature on the dashboard or infotainment display is blank, shows dashes (--), or is stuck at an illogical value (like -40°F).
• The automatic climate control system does not work correctly or defaults to a manual mode.
• The A/C system may not engage or blow cold air because the computer receives an implausible temperature reading (e.g., -40°F).
• The driver and passenger temperature settings may unexpectedly display in Celsius.
• The radiator cooling fan may run continuously or at incorrect times because the computer is receiving faulty data.

Most Likely Causes

1. Faulty Ambient Air Temperature Sensor 🔴 High Probability → Shop Ambient Air Temperature Sensor The sensor is exposed to the elements at the front of the vehicle, leading to failure from moisture, age, or physical damage. It is the most common failure point for this code.
   How to confirm: After checking wiring, replacing the sensor is the most straightforward diagnostic step due to its low cost. A scan tool may show an illogical, fixed temperature reading like -40°F, which indicates an open circuit.
   Typical fix: Replace the ambient air temperature sensor.
   Est. part cost: $15-$40
2. Damaged Wiring or Connector 🟡 Medium Probability The sensor's wiring is located in a vulnerable position behind the front grille and can be damaged by road debris, front-end impacts, or corrosion.
   How to confirm: Visually inspect the wiring harness and connector for cuts, corrosion, or loose pins. TSB #PIC5656F specifically instructs checking that the sensor is connected first. If the connector is damaged, a replacement pigtail (like GM part 12052641) can be spliced in.
   Typical fix: Repair the damaged section of the wiring harness or clean/replace the connector pigtail.
   Est. part cost: $5-$30 for connectors or wiring repair supplies.
3. Instrument Panel Cluster (IPC) Fault ⚪ Low Probability
   How to confirm: This is the least likely cause. If a new sensor and confirmed good wiring do not fix the problem, the IPC itself may be faulty. This requires advanced diagnostics. However, TSB PI0233D explicitly warns technicians *not* to replace the cluster for inaccurate readings, as other causes are far more likely.
   Typical fix: The Instrument Panel Cluster would need to be repaired or replaced by a specialist.
   Est. part cost: $300-$800+

Diagnosis Steps

1. Verify the symptom: Check the outside temperature display for blank, dashed, or incorrect readings (e.g., -40°F).
2. Scan for codes: Use an OBD-II scanner capable of reading Body (B) codes to confirm B0158 is present. The code description may read 'Outside Air Temperature Sensor Circuit Short or Open'.
3. Locate the sensor: On the 2010-2014 LaCrosse, the sensor (labeled B9 in service manuals) is located behind the front grille, typically clipped into the radiator support or a nearby bracket, often slightly to the driver's side of the vehicle's centerline.
4. Inspect sensor and connector: Following TSB #PIC5656F, first ensure the sensor is securely connected. Check the connector and visible wiring for corrosion, damage, or loose pins.
5. Test the circuit (Recommended): 🎬 Watch: How to test and replace the sensor for AC issues. Unplug the sensor's two-pin connector. With the key on, the display should read an extreme cold temperature (-40°F) and a 'circuit high' DTC should set. Next, use a small jumper wire to connect the two terminals in the harness-side connector. The display should now read an extreme hot temperature and a 'circuit low' DTC should set. If both of these tests pass, the wiring and IPC are good, confirming the sensor itself is the fault.
6. Test the sensor (Advanced): Using a multimeter set to Ohms (Ω), measure the resistance across the two pins of the sensor itself. The resistance should change with temperature. A typical thermistor of this type might read around 10,000 Ohms at 77°F (25°C). An open circuit (infinite resistance) or short (zero resistance) indicates a bad sensor.
7. Replace the sensor: 🎬 See this walkthrough for replacing the sensor on a similar GM vehicle. Given the low cost of the part, if the wiring appears intact or tests good, the most effective next step is to replace the sensor.
8. Confirm the repair: After installation, clear any stored DTCs. Turn the key to the 'On' position and verify that the outside temperature display now shows a plausible reading. It may take a few minutes of driving for the reading to fully stabilize.

Parts You'll Likely Need

• Ambient Air Temperature Sensor (OEM #25775833 (supersedes 10396844, 15035786)) — This sensor is the most common point of failure for the B0158 code due to its exposed location and operating environment.
  Trusted brands: ACDelco, GM Genuine Parts, NTK, Standard Motor Products, Dorman
  OEM price range: $20-$40
  Aftermarket price range: $10-$30
• Ambient Air Temperature Sensor Connector Pigtail (OEM #12052641 (example)) — Needed if the original connector or wiring attached to it is corroded, brittle, or physically damaged.
  Trusted brands: ACDelco, Dorman, Various aftermarket
  OEM price range: $20-$35
  Aftermarket price range: $10-$20

Technical Service Bulletins (TSBs) & Recalls

• PIC5656F: Addresses B0158 with symptoms of a missing outside temperature display or a switch to Celsius, instructing technicians to first check the sensor connection and wiring integrity.
• PI0233D: Addresses inaccurate or slow-to-update temperature readings, explaining it's often normal system behavior and warning against replacing the instrument cluster.

Platform-Specific Known Issues

• GM Technical Service Bulletin PIC5656F directly addresses code B0158 on the 2010-2013 LaCrosse. It notes that symptoms can include a missing temperature display or the climate control defaulting to Celsius. The bulletin's primary instruction is to first check if the sensor is disconnected or if the wiring is faulted before performing deeper diagnostics.
• GM Technical Service Bulletin PI0233D addresses complaints of 🎬 Watch: Troubleshooting incorrect temperature readings on a Buick. inaccurate or slow-to-update temperature displays on the 2010-2013 LaCrosse. It explains that an intentional delay is programmed to prevent false high readings after the car has been parked in the sun. It explicitly warns 'DO NOT replace the instrument cluster for this condition'.

Mechanic-Grade Diagnostic Values

• Sensor Resistance vs. Temperature — expected: ~32.7 kΩ at 0°C/32°F; ~12.3 kΩ at 20°C/68°F; ~10.0 kΩ at 25°C/77°F; ~3.0 kΩ at 60°C/140°F. Failure: Infinite resistance (open circuit), near-zero resistance (short circuit), or a value that does not change with temperature.
• Sensor Signal Circuit Voltage — expected: Approx. 5.0 Volts (Key On, sensor disconnected, measured at the harness connector). Failure: 0V indicates an open wire from the IPC or a faulty IPC. Significantly lower voltage suggests a short to ground.
• Low Reference Circuit Resistance to Ground — expected: Less than 10 Ohms (Key Off, measured at the harness connector). Failure: High or infinite resistance indicates an open in the low reference circuit back to the IPC.
• Scan Tool 'Ambient Air Temperature' Parameter (DTC Trigger) — expected: A plausible real-world temperature.. Failure: A reading of -40°C (-40°F) triggers B0158 05 (Open/High Resistance). A reading above 88°C (190°F) triggers B0158 02 (Short to Ground).

Hidden / Shadow Codes Worth Checking

• B0158 02: Ambient Air Temperature Sensor Circuit Short to Ground. The IPC sets this when it detects a sensor signal indicating a temperature over 88°C (190°F). (see via GM-specific scan tool (GDS2/Tech2) or high-end professional scanner capable of reading symptom bytes.)
• B0158 05: Ambient Air Temperature Sensor Circuit High Voltage/Open. The IPC sets this when it detects a sensor signal indicating a temperature below -40°C (-40°F). (see via GM-specific scan tool (GDS2/Tech2) or high-end professional scanner capable of reading symptom bytes.)

Scan Tool Commands That Help

• GDS2 / Tech2: Observe 'Ambient Air Temperature' Parameter — This is the primary live data point for diagnosis. With the sensor unplugged, it should read -40°F. With the harness connector pins jumped, it should read a very high temperature. This confirms the integrity of the wiring and the IPC's ability to read the circuit.

Wiring & Ground Locations

• B9 — Behind the front grille, mounted on the radiator core support.. This is the official GM component designator for the Ambient Air Temperature Sensor itself.
• Circuit 61 (Signal) & 636 (Low Reference) — Wiring harness between the sensor connector (X411) and the Instrument Panel Cluster connector (P16).. These are the specific circuits that carry the temperature signal and its ground reference. TSB PIC5656F directs technicians to check the integrity of these two wires if the sensor is connected but the code persists.
• G103 — On the cowl in the engine compartment, typically located above the brake booster.. This is a primary ground point for the Instrument Panel Cluster (IPC). A corroded or loose G103 can cause erratic behavior in the IPC, including incorrect readings from various sensors, potentially setting a B0158 code even if the sensor and its direct wiring are good.

OEM Part Supersession History

• 10396844, 15035786 → 25775833 — Part consolidation and potential minor revisions.
  Heads up: No known incompatibilities. The new part number is the correct service replacement for the original parts.

Model Year Variations Within This Range

• 2010-2014: No significant variations have been noted for this specific repair within this model year range. The sensor, location, and diagnostic procedure are consistent.