Investigating P0135 in Your 2020 Dodge Charger
When your 2020 Dodge Charger's check engine light illuminates with a P0135 diagnostic code, it's revealing a malfunction in the oxygen sensor heater circuit for Bank 1, Sensor 1. Understanding this code requires knowing your Charger's engine configuration, as the seventh-generation Charger offers multiple powertrain options. The base engine is the 3.6L Pentastar V6 producing 292 horsepower, while performance models feature either the 5.7L HEMI V8 (370 hp) or the 6.4L HEMI V8 (485 hp in Scat Pack models).
For all V6 and V8 configurations, Bank 1 refers to the cylinder bank that includes cylinder number one, typically the passenger side on Chrysler V-engines. Sensor 1 is the upstream oxygen sensor positioned before the catalytic converter in the exhaust manifold or header pipe. This sensor's heater element is designed to rapidly warm the sensor tip to approximately 600°F within 30 seconds of engine startup, enabling quick transition to closed-loop fuel control for optimal efficiency and emissions.
The 2020 Charger continues the proven LD platform that debuted in 2011, with the final major refresh occurring in 2015. The exhaust systems differ significantly between engine options: V6 models use a single catalytic converter with two upstream O2 sensors (one per bank), while HEMI V8 models feature dual exhaust with independent cats and O2 sensors for each bank. This means V8 Chargers have twice the O2 sensors that could potentially fail, though P0135 specifically addresses Bank 1.
Recognizing the Telltale Symptoms
The P0135 code manifests through several observable symptoms that help confirm the diagnosis beyond the illuminated check engine light. In your 2020 Charger, the most prominent sign appears during cold starts, particularly on mornings when temperatures drop below 50°F. The engine may idle slightly rough for the first minute, with RPM fluctuations between 600-800 for V6 models or 650-850 for HEMI V8s, rather than settling at the smooth target idle speed. This roughness typically resolves as the O2 sensor gradually warms through exhaust heat.
Fuel economy degradation provides a reliable indicator. The EPA rates the 2020 Charger at 19 city/30 highway for the V6, 15/25 for the 5.7L HEMI, and 13/22 for the 6.4L HEMI in Scat Pack models. With P0135 active, expect a 1-3 mpg decrease in mixed driving. For V6 models averaging 24 mpg combined, this drops to 21-23 mpg. HEMI owners seeing 18-20 mpg might notice a decline to 16-18 mpg. Given the Charger's 18.5-gallon fuel tank, this translates to an extra $15-30 per tank depending on local fuel prices and your specific engine.
Performance characteristics reveal additional clues. During the first 5-10 minutes after a cold start, V6 Chargers may exhibit slightly sluggish throttle response when accelerating from stops. HEMI V8 models, particularly the 392 Scat Pack with its 6.4L engine, may feel less eager during warmup and take longer to fully wake up. The sophisticated engine management systems in these performance engines rely heavily on accurate O2 sensor feedback to optimize ignition timing and fuel delivery. Without proper sensor warmup, the PCM defaults to conservative calibrations that prioritize reliability over responsiveness.
Some Charger owners report detecting a faint sulfur or rotten egg smell from the exhaust during the warmup period. This odor indicates the catalytic converter is working harder to clean up slightly richer exhaust gases when the engine operates in open-loop mode. The smell typically fades once closed-loop operation resumes after the sensor reaches operating temperature through exhaust heat alone.
V8 Charger owners may notice the active exhaust system (if equipped) behaving differently during warmup, potentially staying in quiet mode longer than usual as the PCM operates conservatively. The cylinder deactivation system in 5.7L HEMI models (MDS - Multi-Displacement System) might engage less frequently during warmup without accurate O2 sensor feedback, affecting both fuel economy and the characteristic V8 sound profile.
Deducing the Root Causes
Systematic investigation of P0135 codes across 2020 Charger models reveals four primary failure mechanisms, with some variation between V6 and V8 configurations.
Failed Oxygen Sensor Heater Element (47% likelihood): Internal heater element failure dominates P0135 cases in seventh-generation Chargers. The sensor contains a small ceramic resistor coil designed to draw 0.8-1.2 amps and generate rapid heating to sensor operating temperature. Thermal cycling from repeated warmup and cool-down cycles eventually causes microscopic cracks in the element or its internal connections. HEMI V8 models, particularly the high-performance 6.4L engines, generate significantly hotter exhaust temperatures than the V6—peak temps can reach 1500-1700°F under full throttle. This extreme thermal environment accelerates sensor aging. Chrysler typically sources Bosch or NTK oxygen sensors for Charger applications, with design life of 80,000-120,000 miles under normal driving conditions. Spirited driving in performance models can reduce this lifespan. A healthy heater circuit measures 2-10 ohms resistance at room temperature. Infinite resistance indicates an open circuit, while near-zero resistance suggests an internal short.
Wiring Damage or Connector Corrosion (32% likelihood): The Charger's performance-oriented exhaust routing places O2 sensor wiring in proximity to high-temperature exhaust components. On V6 models, both upstream sensors mount in the exhaust manifolds with wiring routed along the engine valley. HEMI V8 models have sensors in each exhaust header pipe with wiring running close to the exhaust along the frame rails. The electrical connectors, typically located near the transmission bellhousing area or along the inner fenders, can accumulate moisture and develop terminal corrosion over time. Road spray containing salt accelerates this corrosion, making it more prevalent in northern climates. The sensor wiring uses thin 18-20 gauge conductors with heat-resistant insulation, but prolonged exposure to temperatures exceeding 400°F can degrade this protection. Enthusiast Charger owners who modify exhaust systems sometimes inadvertently damage O2 sensor wiring during header or cat-back installation, creating immediate or delayed failures.
Blown Fuse or Relay Fault (13% likelihood): The O2 sensor heater circuits in the 2020 Charger draw significant current (multiple sensors operating simultaneously) and are protected by dedicated fuses in the Integrated Power Module located in the engine bay. V6 models typically use 15-amp fuses, while V8 models may use 20-amp fuses due to having four upstream sensors total. Fuses rarely fail spontaneously in modern vehicles, but short circuits elsewhere in the heater system can blow the fuse as a protective measure. The relay that switches power to the heater circuits under PCM control can develop internal contact degradation, though this is less common in vehicles under five years old. Checking the fuse should always be your first diagnostic step due to accessibility and minimal cost.
PCM Software or Driver Circuit Issue (8% likelihood): The powertrain control module in the 2020 Charger is a sophisticated computer managing hundreds of sensors and actuators. Occasionally, the internal driver circuit that powers individual O2 sensor heaters can fail, preventing heater operation despite having a good sensor and intact wiring. More commonly, calibration issues in the PCM software might incorrectly flag P0135 when the circuit is functioning properly—a false positive. Chrysler periodically releases software updates addressing various sensor monitoring parameters and driveability refinements. If your Charger has never received PCM updates since purchase, checking for available calibrations is worthwhile. Complete PCM hardware failure is rare and would typically present with multiple unrelated codes plus significant driveability issues.
Diagnostic Investigation Procedures
Properly diagnosing P0135 in your 2020 Charger requires methodical testing with appropriate tools. You'll need an advanced OBD-II scanner with live data capability (not just a basic code reader), a quality digital multimeter, and basic hand tools. If you plan sensor removal, a 22mm O2 sensor socket is essential for V6 models, while HEMI V8s may use 7/8-inch sensors. Safety first: allow the exhaust system to cool completely before working near sensors or manifolds—high-performance engines retain heat extensively.
Begin by connecting your scanner and retrieving all diagnostic codes, both active and pending. Note whether P0135 appears alone or with companion codes like P0155 (Bank 2 Sensor 1 heater circuit), P0131 (Bank 1 Sensor 1 low voltage), or P0420/P0430 (catalyst efficiency). Review freeze frame data showing conditions when P0135 first set: coolant temperature, vehicle speed, and runtime are particularly relevant. Codes setting immediately at cold start strongly indicate heater circuit issues.
Navigate to live data and locate O2 sensor heater command parameters. With key-on-engine-off, the PCM should command all heater circuits active immediately. Simultaneously monitor the Bank 1 Sensor 1 voltage signal—even a cold sensor should show some activity between 0.1-0.9V. If the heater command is active but sensor voltage remains flat, suspect a failed heater element preventing proper warmup.
Visually inspect the Bank 1 Sensor 1 location. For V6 Chargers, this is in the passenger-side exhaust manifold, accessed from above with some difficulty due to the transverse engine mounting. For HEMI V8 models with longitudinal engine orientation, the passenger-side upstream sensor is more accessible from underneath the vehicle. Trace the wiring to its connector and inspect for damage, melted insulation, or obvious issues. Disconnect the connector and examine both halves for corrosion or pushed-back terminals.
With the connector separated, use your multimeter in ohms mode to test heater circuit resistance. On Chrysler four-wire O2 sensors, the heater circuit typically uses specific pins (consult a wiring diagram for your exact configuration). Measure resistance across the heater terminals on the sensor side—you should read 2-10 ohms at room temperature. Infinite resistance indicates an open circuit, near-zero resistance suggests a short. Also check insulation by measuring resistance from each heater terminal to the sensor body—infinite resistance confirms proper insulation.
If the sensor tests good, check the vehicle harness. With the connector still separated, switch your meter to DC voltage mode. Key on, engine off, measure voltage at the harness connector. You should see battery voltage (12-14V) on one terminal and ground (0-0.5V) on the other when the PCM commands the heater on. No voltage indicates wiring issues, a blown fuse, or PCM driver circuit problems.
Finally, check the O2 sensor heater fuse in the Integrated Power Module (IPM) under the hood. Your owner's manual provides fuse locations. Remove the appropriate fuse and visually inspect the metal element—a blown fuse shows a broken element. Confirm with your multimeter's continuity function.
Repair Solutions and Cost Analysis
For most 2020 Charger owners, replacing the Bank 1 Sensor 1 oxygen sensor resolves P0135 in about 75% of cases. Parts pricing varies by engine: genuine Mopar sensors cost $140-$220 for V6 models and $150-$240 for HEMI V8 applications. Quality aftermarket alternatives from Bosch, Denso, or NTK range from $85-$160 for V6 sensors and $90-$175 for HEMI sensors.
Professional installation at a Dodge dealer typically costs $260-$420 total (parts and labor) for V6 models, with labor running $120-$180 for 1.0-1.5 hours. HEMI V8 sensor replacement is slightly more accessible from underneath, averaging $240-$380 total. Independent shops often charge less, around $220-$350 for V6 models and $200-$320 for V8 models.
DIY replacement is feasible with moderate skills. For V6 Chargers, top-side access is challenging but possible with patience. You'll need a 22mm O2 sensor socket, ratchet with extensions, and anti-seize compound. Allow 90-120 minutes for first-timers. HEMI V8 models are easier from underneath on jack stands or ramps, taking 45-75 minutes. Ensure the engine is completely cool. Procedure: disconnect battery negative terminal, disconnect sensor electrical connector, use O2 sensor socket to remove old sensor, clean threads in manifold/pipe, apply anti-seize to new sensor threads (avoid the tip), hand-thread into place, torque to 30-35 ft-lbs, reconnect wiring and battery, clear codes. Total DIY cost: $85-$240 depending on parts selection.
Wiring repairs vary by extent. Connector cleaning costs $70-$130 at shops. Single wire repair runs $90-$180. Complete sub-harness replacement reaches $220-$400 including labor. DIY wiring repairs using quality crimp connectors and heat shrink tubing cost $15-35 in materials.
A blown fuse is cheapest at $3-$8, though identifying the cause is essential. PCM software updates cost $100-$180 at dealers, while complete PCM replacement (rarely needed) reaches $600-$1,100 including programming.
HEMI V8 owners should note: if Bank 1 fails, Bank 2 may follow soon. With vehicles over 80,000 miles, consider replacing both upstream sensors simultaneously to save future labor costs.
Prevention Tips for Charger Owners
Several practices extend O2 sensor life in your performance-oriented Charger. Use only the specified fuel grade: 87 octane regular for 3.6L V6, 89 octane mid-grade recommended (87 acceptable) for 5.7L HEMI, and 91 octane premium required for 6.4L HEMI. Use top-tier detergent gasoline from major brands to minimize combustion deposits.
Avoid unnecessary fuel additives or octane boosters unless addressing specific documented issues. Many additives contain compounds that can contaminate O2 sensors. Monitor oil consumption—any engine burning oil exposes sensors to ash that shortens lifespan. Check oil monthly; investigate if adding more than a quart between 5,000-mile service intervals.
Follow Dodge's maintenance schedule precisely: oil changes per the Oil Change Indicator system (typically 4,000-6,000 miles depending on driving style), spark plug replacement at 100,000 miles for V6 or 30,000 miles for HEMI V8s (note the significant difference), and air filter inspection at every service. Worn plugs cause misfires that contaminate sensors and cats.
For spirited drivers enjoying the Charger's performance capabilities, implement cool-down procedures after hard driving. Let the engine idle 60-90 seconds after track time or aggressive highway runs to normalize exhaust temperatures gradually rather than shocking sensors and turbochargers with sudden shutdown.
In northern climates, periodically spray sensor connectors with electrical contact cleaner and apply dielectric grease to prevent corrosion. Inspect connectors during oil changes or underhood maintenance.
When Professional Diagnosis Is Warranted
Several scenarios warrant professional assistance over DIY troubleshooting. If you're uncomfortable with electrical diagnostics or multimeter use, the $100-$160 diagnostic fee is worthwhile compared to incorrect parts replacement. Professional technicians access Chrysler's factory service information, wiring diagrams, and technical service bulletins unavailable publicly.
If you replace the sensor but P0135 returns immediately or within a few hundred miles, underlying electrical issues require professional diagnosis with dealer-level equipment. Intermittent codes that appear and disappear randomly indicate difficult-to-trace wiring problems best left to experienced technicians.
When P0135 appears with multiple companion codes—particularly catalyst codes, fuel system codes, or multiple O2 sensor codes—the issue likely extends beyond simple heater failure. This suggests broader exhaust or engine management problems requiring comprehensive professional diagnosis.
If your 2020 Charger remains under Chrysler's factory warranty (3 years/36,000 miles basic, 5 years/60,000 miles powertrain), always start with your Dodge dealer. Repairs will be covered at no cost, and proper documentation protects you for related future issues. Dealers can check for unpublicized technical service bulletins specific to your VIN and production date.
For performance-modified Chargers (aftermarket exhausts, tunes, forced induction), professional diagnosis is strongly recommended. Modifications can affect O2 sensor operation and PCM monitoring parameters in ways that require experienced interpretation to diagnose correctly.