P1058 on 2008-2009 Pontiac G8 3.6L: Code Definition Uncertain

What's Unique About the 2008-2009 Pontiac G8

The Pontiac G8 and its 3.6L LY7 engine are not commonly associated with the code P1058 in enthusiast communities or repair literature. Searches for this specific code on G8-centric forums and even forums for its Australian counterpart, the Holden Commodore VE, yield no results. This lack of information is significant and strongly suggests the code may be incorrect. Owners of this engine more frequently report issues with timing chains (e.g., code P0008, P0009) or standard oxygen sensor codes.

Symptoms You May Notice

• Symptom data is unavailable as the code definition is not confirmed for this vehicle.
• If the code is a typo for P0158 or P0058, symptoms may include poor fuel economy, rough idling, and a noticeable smell of gasoline from the exhaust.

Most Likely Causes

1. Incorrect Code / Typo 🔴 High Probability P1xxx codes are rare compared to P0xxx codes. It is common for users or basic scanners to misread a code. The lack of any official or anecdotal report of P1058 for this GM platform makes a typo the most probable cause.
   How to confirm: Re-scan the vehicle's computer, preferably with a different, high-quality OBD-II scanner. Confirm if the code is actually P0158 (O2 Sensor Circuit High Voltage Bank 2 Sensor 2) or P0058 (HO2S Heater Control Circuit High Bank 2 Sensor 2).
   Typical fix: Address the actual trouble code found after re-scanning. For P0158/P0058, this often involves replacing the downstream oxygen sensor on Bank 2 (the cylinder bank closer to the firewall).
   Est. part cost: $0

Diagnosis Steps

1. Confirm the code: Use a reliable OBD-II scanner to re-read the trouble codes from the Engine Control Module (ECM). Verify that the code is truly P1058.
2. Check for other codes: Note any other codes that are present. If you see P0158 or P0058, those are the codes you should diagnose.
🎬 Watch: How to diagnose and fix the P0158 O2 sensor code
3. Diagnose the Likely Typo (P0158/P0058): Bank 2 is the side of the engine closer to the firewall. Sensor 2 is the downstream sensor, located after the catalytic converter. Inspect the wiring harness and connector for damage. Test the sensor's heater circuit and voltage output. Often, the simplest fix is to replace the sensor.
4. If P1058 is confirmed: The vehicle should be taken to a qualified technician who has access to GM's specific diagnostic software (Tech2Win or GDS2). Generic tools may not be able to interpret this code correctly, and it is not present in published GM-specific code lists.
5. Follow professional guidance: Diagnosis from this point depends entirely on the definition provided by GM's proprietary software, if one exists at all.

Parts You'll Likely Need

• Oxygen Sensor (Bank 2, Sensor 2)

Related Codes That Often Appear With This One

• P0158 — This is a possible typo. P0158 means 'O2 Sensor Circuit High Voltage (Bank 2, Sensor 2),' indicating a problem with the downstream oxygen sensor on the driver's side (firewall side). This can be caused by a failed sensor, wiring issues, or an engine running rich.
• P0058 — This is a possible typo. P0058 means 'HO2S Heater Control Circuit High (Bank 2, Sensor 2),' pointing to a fault in the heating element of the same oxygen sensor. This is a common failure mode for O2 sensors.
• P0008 / P0009 — While not a typo, these are very common codes on the LY7 engine related to stretched timing chains. If other driveability issues are present, it's worth noting if these codes are also stored, as timing issues are a well-documented problem for this engine.

Technical Service Bulletins (TSBs) & Recalls

• No TSBs related to P1058 for this platform were found during an expanded search of GM and public databases.

Mechanic-Grade Diagnostic Values

• HO2S Heater Circuit Resistance (for P0058) — expected: Typically 2–20 Ω, but must be compared to manufacturer spec for the specific sensor.. Failure: Infinite resistance (open circuit) or near-zero resistance (short circuit).
• HO2S Heater Circuit Voltage (for P0058/P0158) — expected: Approximately 12V (battery voltage) at the heater supply pin with key on, engine off.. Failure: Voltage significantly above 12V confirms a 'Circuit High' condition. No voltage could indicate a blown fuse or wiring issue upstream.
• HO2S Signal Voltage (for P0158) — expected: Downstream sensor (Sensor 2) should show a steady voltage, typically between 0.5V and 0.8V, if the catalytic converter is working well.. Failure: A voltage stuck 'high' (above 0.9V) for an extended period will trigger P0158. This indicates a rich condition, a short in the signal wire, or a failed sensor.

Scan Tool Commands That Help

• Tech2 / GDS2: O2 Sensor Heater Diagnostics — If P0058 is the suspected actual code, a GM-specific tool can command the heater circuit on and off to test the response of the ECM driver, relay, and the sensor's heating element itself.
• Professional Scan Tool with Live Data: Live Data Graphing - O2 Sensor Voltage — To diagnose P0158, monitoring the live voltage of Bank 2, Sensor 2 is essential. A healthy sensor will show relatively stable voltage, while a faulty one might be stuck high, low, or show erratic patterns.

Wiring & Ground Locations

• Bank 2, Sensor 2 — In the exhaust system, after the left (firewall side) catalytic converter.. This is the location of the sensor and wiring that needs to be inspected if the actual code is P0158 or P0058.
• G112 — Ground point from the left rear cylinder head to the engine harness.. A poor engine ground can cause a variety of sensor and module communication issues, including erratic voltage readings that could potentially trigger a 'Circuit High' code. Ensuring this ground is clean and tight is a critical diagnostic step for any electrical fault.
• G108 / G109 — G108 is at the right rear of the engine block; G109 is at the left middle of the engine block.. These are primary engine block grounds. A fault at these locations can affect the entire engine management system and should be checked when diagnosing any electrical DTC.
• ECM (Engine Control Module) — Located on the right side of the engine compartment.. The ECM is the source of the control signal for the O2 sensor heater and interprets the voltage readings. All wiring for the O2 sensor terminates here, making its connectors a key inspection point.

OEM Part Supersession History

• 92210450 → No supersession found. — The part number appears to be stable for the specified application.
  Heads up: While no direct supersession was found, an Australian parts supplier notes a difference in 4-pin vs 6-pin connectors on some Holden Commodore LY7 engines. Visual confirmation of the connector is recommended before ordering.

Model Year Variations Within This Range

• 2008 vs 2009: Minor changes occurred between 2008 and 2009, such as the removal of the center stack 'Atari' gauges, different water pump/radiator hose on some '09s, and the addition of Bluetooth on late '09.5 models. However, no changes were identified related to the engine management, exhaust, or O2 sensor systems for the LY7 V6 that would alter the diagnosis of P1058 or its likely typo-equivalents.

Diagnostic Flowchart

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: Never. Oxygen sensors are wear items with a finite lifespan. The heating element degrades over time, and the sensing element becomes contaminated. A used sensor has unknown life remaining and is a poor value proposition.

What to inspect on the donor part:

• Not applicable. Do not purchase used oxygen sensors.

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

• While not strictly 'OEM-only', using a high-quality OEM or OEM-supplier brand for oxygen sensors is highly recommended. Cheaper, no-name sensors are notorious for failing prematurely, having incorrect calibrations that hurt fuel economy, or not meeting emissions standards.

Aftermarket brands forum-validated for this vehicle:

• ACDelco (Original GM part)
• Denso (Often the original equipment manufacturer for GM)
• NTK (Also a top-tier OEM supplier)

Brands owners have reported issues with on this vehicle:

• While some owners have success, Bosch sensors can have compatibility issues on certain GM vehicles, with forum members sometimes advising to stick with Denso or ACDelco to be safe.
• Unbranded, low-cost sensors from online marketplaces should be avoided as their quality and calibration are often questionable.

Related OBD-II Codes

• P0158 — Considered the most likely actual code if P1058 is a typo. It indicates a high voltage condition in the Bank 2, Sensor 2 oxygen sensor circuit, often caused by a failed sensor.
• P0058 — Another highly probable code that P1058 is a typo for. This code points specifically to a fault in the heater control circuit of the Bank 2, Sensor 2 oxygen sensor.
• P0008 — While unrelated to the oxygen sensor issue, this code for 'Engine Position System Performance' is a known issue on the shared 3.6L LY7 V6 engine platform, often indicating a serious timing chain problem.

Frequently Asked Questions