🧭 Diagnostic Flowchart 🎬 Helpful Videos 🛍️ Shop This Part

P0137 on 2017-2024 Chrysler Pacifica 3.6L: O2 Sensor Low Voltage Causes and Fixes

The P0137 code on a 2017-2024 Chrysler Pacifica most often means the rear downstream oxygen sensor (Bank 1, Sensor 2) has failed. This sensor is difficult to access against the firewall, making the repair more labor-intensive. Before replacing the sensor, inspect for oil leaks from the rear valve cover, as oil contamination of the sensor's connector is a known issue. Expect to pay $40-$80 for an aftermarket sensor and $100-$150 for an OEM equivalent.

21 minutes to read 2017-2024 Chrysler Pacifica

Most Likely Cause

Failed Bank 1, Sensor 2 Oxygen Sensor

Difficulty

4/5

Est. Time

2.2 hrs

DIY Doable?

🔧 Shop

Shop Labor

$250 – $550

Parts Price

$40 – $150

⚠️ Drivable, but... — Yes, you can drive with a P0137 code, as it typically does not cause immediate drivability issues. However, ignoring it long-term can mask a failing catalytic converter and will cause your vehicle to fail an emissions test.

Key Takeaways

P0137 on your Pacifica points directly to the downstream oxygen sensor on the rear cylinder bank (Bank 1).
The most common fix is to replace the oxygen sensor itself, but it is critical to use an OEM or OES brand like Mopar or NTK.
Before replacing parts, always inspect the rear valve cover for oil leaks and check the sensor's wiring and connector for damage or oil contamination, as these are common and cheaper-to-fix issues.
The primary challenge with this repair is the sensor's location against the firewall, which makes it a labor-intensive job.
While you can drive the vehicle, it's best to address the issue to ensure your vehicle can pass emissions and to avoid potentially masking more serious catalytic converter problems.

The trouble code P0137 stands for 'Oxygen Sensor Circuit Low Voltage (Bank 1, Sensor 2)'. This means the Powertrain Control Module (PCM) has detected that the voltage signal from a specific oxygen sensor is below the normal operating range (stuck under 0.2V) for an extended period. 'Bank 1' on the Pacifica's 3.6L V6 refers to the cylinder head located at the rear of the engine, against the firewall. 'Sensor 2' is the downstream sensor, positioned in the exhaust pipe after the catalytic converter, where its main job is to monitor the converter's efficiency.

What's Unique About the 2017-2024 Chrysler Pacifica

On the front-wheel-drive Pacifica, the 3.6L Pentastar engine is mounted transversely. This places Bank 1 (the rear cylinder bank) directly against the firewall, making access to its components notoriously difficult. While the P0137 code itself is straightforward, replacing the Bank 1, Sensor 2 oxygen sensor is a more involved job than on many other vehicles. Mechanics or DIYers may need to remove other components, like the upper intake manifold, to gain adequate access, which significantly increases labor time and cost.

Symptoms You May Notice

Check Engine Light is on
Failing an emissions test
Slight decrease in fuel economy in some cases
Rough or unstable idle (less common)
Noticeable exhaust fume odor (uncommon)

⚠️ Don't Waste Money on the Wrong Fix

Replacing the wrong oxygen sensor (e.g., replacing the Bank 2 sensor or the upstream Sensor 1).
Replacing the catalytic converter before properly diagnosing the O2 sensor and its circuit.
Replacing the O2 sensor without addressing an underlying oil leak from the valve cover that is contaminating the connector.

Most Likely Causes

Failed Bank 1, Sensor 2 Oxygen Sensor 🔴 High Probability → Shop Oxygen Sensor Oxygen sensors are wear-and-tear items that operate in a harsh exhaust environment and have a finite lifespan, typically around 70,000 to 100,000 miles. Owners and technicians widely report that Pentastar engines are sensitive to aftermarket sensors, making OEM/OES parts (Mopar, NTK, Denso) highly recommended to avoid repeat failures.
How to confirm: Using an OBD-II scanner with live data, monitor the voltage of the Bank 1, Sensor 2. A healthy downstream sensor should show a relatively stable voltage (typically around 0.6-0.8V). If the voltage is stuck low (below 0.2V) or is not responding, the sensor is likely faulty. 🎬 Watch: This video explains the common causes of low O2 voltage.
Typical fix: Replace the Bank 1, Sensor 2 oxygen sensor. Due to its location against the firewall, this is more labor-intensive than replacing the Bank 2 sensor.
Est. part cost: $40-$150
Damaged Wiring or Connector 🟡 Medium Probability The wiring harness for the O2 sensor is located under the vehicle and is exposed to road debris, moisture, and extreme heat from the exhaust, which can cause corrosion or physical damage over time.
How to confirm: Visually inspect the wiring harness and connector leading to the Bank 1, Sensor 2 for any signs of melting, chafing, corrosion, or loose pins. A multimeter can be used to check for continuity and proper voltage/ground at the connector.
Typical fix: Repair the damaged section of wiring or clean/replace the connector. Ensure repairs are sealed against moisture.
Est. part cost: $10-$50
Oil Leak from Valve Cover Gasket 🟡 Medium Probability → Shop Engine Valve Cover The 3.6L Pentastar engine family is known for valve cover gaskets that can leak oil. On platforms like the Jeep Wrangler, oil from the Bank 1 (passenger side) valve cover is known to drip directly onto the Bank 1, Sensor 2 connector, saturating it and causing an electrical short that triggers P0137. This should be inspected as a possible root cause on the Pacifica as well. Manufacturer TSB Bulletin #9003790 specifically notes that oil leaking from the valve cover onto the O2 sensor can cause fault codes including P0137, and technicians should verify if the gasket is pinched, out of position, rolled, or cut.
How to confirm: Inspect the area around the rear (Bank 1) valve cover and down the side of the engine block towards the exhaust for signs of fresh or caked-on oil. Check the O2 sensor's electrical connector for oil contamination.
Typical fix: First, replace the leaking valve cover gasket. Then, thoroughly clean the oil from the O2 sensor connector with electrical contact cleaner. If the code returns, replace the oxygen sensor itself.
Est. part cost: $50-$250 (for gasket set and sensor)
Exhaust Leak ⚪ Low Probability
How to confirm: Visually inspect the exhaust system from the manifold to the catalytic converter for cracks or loose connections. Listen for an audible ticking or hissing sound, especially when the engine is cold. An exhaust leak before the sensor can introduce outside air, causing a false low voltage reading. A mechanic can perform a smoke test to pinpoint hard-to-see leaks.
Typical fix: Repair the leak by replacing the faulty gasket or welding the cracked component.
Est. part cost: $20-$200

Rare But Worth Checking

Failing Catalytic Converter: While a bad O2 sensor is more common, a P0137 code can sometimes be an early indicator of a catalytic converter that is becoming inefficient. If replacing the sensor doesn't fix the code, the converter's health should be investigated.
PCM Software Issue: Chrysler has issued software updates for other O2 sensor-related codes on this platform. TSB 18-059-16 was a powertrain flash for earlier 3.6L engines to address overly sensitive calibrations. It's worth checking with a dealer for any applicable PCM updates before performing major repairs.

Diagnosis Steps

Connect an OBD-II scanner and confirm the presence of the P0137 code. Note any other codes present.
Using the scanner's live data stream, observe the voltage from the Bank 1, Sensor 2 O2 sensor. It should be relatively stable. If it's stuck below 0.2V, the sensor or circuit is the likely problem.
Perform a thorough visual inspection of the rear (Bank 1) valve cover for any signs of oil leaks dripping down toward the exhaust and O2 sensor.
Perform a thorough visual inspection of the Bank 1, Sensor 2 wiring and connector. Look for any signs of damage, melting, oil contamination, or corrosion. The sensor is on the rear exhaust manifold, after the catalytic converter.
Inspect the exhaust system for any leaks between the engine and the O2 sensor. Listen for hissing or ticking noises when the engine is cold.
If the wiring and exhaust are okay, and there are no oil leaks, the most likely cause is a failed O2 sensor.
Test the sensor's heater circuit. A failed heater can also cause incorrect voltage readings and may set its own specific trouble code. A healthy heater should measure between 3 and 30 ohms.
If a new sensor does not resolve the code, check with a dealer for any available PCM software updates. If none, the issue may be with the PCM, though this is rare.

Parts You'll Likely Need

Oxygen Sensor (Bank 1, Sensor 2) (OEM #05149180AB (This is a common downstream sensor, but always verify with VIN. Note: On some related platforms, this part is the same as the upstream sensors).) — This is the most common component to fail and cause a P0137 code. It is a wear item.
Trusted brands: Mopar (OEM), NTK, Denso, Bosch
OEM price range: $100-$150
Aftermarket price range: $40-$80

Related Codes That Often Appear With This One

P0136 — P0136 indicates a general malfunction in the same O2 sensor circuit (Bank 1, Sensor 2).
P0138 — P0138 is the opposite of P0137, indicating high voltage in the same sensor circuit. Seeing them together could point to an erratic wiring short.
P0420 — P0420 (Catalyst System Efficiency Below Threshold Bank 1) can appear if the P0137 fault is left unaddressed, as the PCM cannot accurately monitor the catalytic converter's performance.
P2096 — P2096 (Post Catalyst Fuel Trim System Too Lean Bank 1) can be caused by an exhaust leak or a faulty O2 sensor giving incorrect lean readings, which are related root causes for P0137.

Technical Service Bulletins (TSBs) & Recalls

TSB 9003756: Pertains to vehicles with the 3.6L V6 engine where oil leaking from the valve cover onto the O2 sensor causes fault codes including P0137.
TSB Bulletin #9003790: This bulletin specifically addresses the 3.6L V6 V.V.T. engine, noting that oil leaking from the valve cover onto the O2 sensor can trigger P0137, P0140, P2096, and P0157.

Platform-Specific Known Issues

Access to the Bank 1 (rear) oxygen sensors is significantly restricted by the firewall and may require removal of the upper intake manifold for replacement, increasing labor time and cost.
The 3.6L Pentastar engine family has a known issue with oil leaks from the valve cover gaskets, which can contaminate the O2 sensor connector and cause this code. TSB 9003756 was issued for other Chrysler vehicles with this engine for oil leaking from the valve cover causing O2 sensor faults like P0137.

Mechanic-Grade Diagnostic Values

Downstream O2 Sensor (B1S2) Signal Voltage — expected: Relatively stable voltage between 0.6V and 0.8V when the catalytic converter is at operating temperature and working efficiently.. Failure: Sustained voltage below 0.2V for an extended period (e.g., 20 seconds) will trigger P0137.
O2 Sensor Heater Element Resistance — expected: Between 3 and 30 ohms when measured across the two heater pins on the sensor connector (often the two same-colored wires). Some sources specify a tighter range of 4-10 ohms for a healthy sensor.. Failure: A reading of infinite resistance (Open Loop / 'OL') or near-zero ohms (short circuit) indicates a failed heater element.
O2 Sensor Heater Circuit Power Supply — expected: Approximately battery voltage (12.0V - 12.6V) with Key On, Engine Off (KOEO) at the harness-side connector.. Failure: A reading near 0V suggests a blown fuse (check F25 in the TIPM), a break in the power wire, or a TIPM/fuse box issue.

Scan Tool Commands That Help

wiTECH (Chrysler Dealer Tool) or high-end aftermarket scanner: O2 Sensor Heater Test — This is a bidirectional command that allows the technician to manually activate the O2 sensor's heater circuit. It is used to verify if the heater element, wiring, fuse, and PCM driver are all functioning correctly without having to wait for the PCM to command it on during a drive cycle. This can quickly isolate a failed heater from a wiring or PCM issue.

Wiring & Ground Locations

O2 Sensor Heater Fuse — Fuse F25 (20A) in the engine bay fuse box, also known as the Totally Integrated Power Module (TIPM). This fuse is often labeled for the 'Automatic Shutdown' (ASD) relay, which powers the O2 heaters.. A blown F25 fuse will cut power to the O2 sensor's internal heater. A cold sensor cannot produce an accurate voltage signal, which can lead to the PCM interpreting the output as an erroneously low voltage, potentially setting a P0137 code, although a heater circuit code (like P0037) is more common.
B1S2 Connector — On the exhaust pipe, downstream of the rear catalytic converter, close to the firewall. The wiring harness runs up the back of the engine.. This connector is the primary point for testing both the sensor and the circuit back to the PCM. It is also susceptible to contamination from oil leaking from the rear valve cover, which can short the signal wire to ground, directly causing a P0137 low voltage reading.

"I Checked Everything" — The Actual Cause

In a related TSB for GM vehicles (18-NA-009), a P0137 code was traced to a leaking power steering hose dripping fluid onto the O2 sensor wiring harness. The fluid contaminated the connector and wiring, causing a signal short to ground. This is an edge case to consider if a visual inspection for oil leaks is clean but the connector appears wet or contaminated with an unknown fluid.

OEM Part Supersession History

5149180AA → 05149180AB — Standard part revision by the manufacturer. The new part is a direct replacement for the old one.

Model Year Variations Within This Range

2021-2024: The Chrysler Pacifica received a significant refresh for the 2021 model year, including updated exterior styling and a new Uconnect 5 infotainment system. While the core 3.6L Pentastar engine remained, wiring harnesses and module software may have changed. Technicians should be aware that TSBs or software updates might be specific to pre- or post-refresh models. For example, TSB 18-050-22 REV A for a related O2 heater code specifically applies to 2021 models.

Diagnostic Flowchart

Start by confirming if P0137 is the sole code or if it's accompanied by oil pressure or misfire codes, as the Pentastar 3.6L is prone to specific fluid-related sensor failures.

Inspect the rear (Bank 1) valve cover near the firewall. Is there evidence of oil leaking down the block toward the exhaust?

Disconnect the Bank 1, Sensor 2 connector. Is there oil inside the electrical plug?

→ This matches TSB 9003756. Replace the leaking valve cover gasket first, then clean the connector with electrical contact cleaner. If the code persists, replace the O2 sensor.

Monitor Live Data for B1S2 Voltage. Does the voltage stay stuck below 0.2V even when the engine is warm?

Inspect the wiring harness leading to the rear sensor. Is there any chafing, melting, or road debris damage?

→ Repair the damaged wiring section and ensure it is sealed against moisture. Secure the harness away from the hot exhaust manifold.

If wiring and exhaust are sealed, the sensor has likely failed internally. Which replacement part will you use?

→ Caution: Pentastar engines are highly sensitive to aftermarket sensors. It is strongly recommended to use Mopar, NTK, or Denso (OES) parts to avoid repeat P0137 codes.

After sensor replacement, does the code return after two drive cycles?

→ Repair successful. Note: Accessing this rear sensor near the firewall is difficult; ensure the heat shield was properly reinstalled.

→ Check for a PCM software update at the dealer. If software is current, the issue may be a rare internal PCM failure or a restricted catalytic converter.

→ The fault may be intermittent. Inspect the exhaust system for small leaks or 'ticking' sounds when cold, which can introduce air and cause false low-voltage readings.