P1622 on 2013-2015 Chrysler 300: O2 Sensor Reference Voltage High Causes and Fixes

What's Unique About the 2013-2015 Chrysler 300

For this generation of Chrysler 300 and its platform-mates (like the Dodge Charger and Challenger), the P1622 code is frequently not caused by a failed part. Multiple Technical Service Bulletins (TSBs) issued by Chrysler point to a software issue within the Powertrain Control Module (PCM) as the primary culprit, especially on models with the 5.7L HEMI engine. Owners often find that the official fix is a PCM software update (reflash) rather than replacing the O2 sensors themselves, which might be the first assumption.

Diagnostic Flowchart

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

Symptoms You May Notice

• Check Engine Light is on
• Rough idling or engine misfires
• Decreased fuel economy
• Poor engine performance or hesitation
• Engine buck or delay feeling during low-speed driving.

Most Likely Causes

1. Powertrain Control Module (PCM) Software Requires Update 🔴 High Probability Manufacturer TSBs #18-073-20, #18-052-15 REV A, #18-084-16, and #18-052-15 all indicate that a software update is the prescribed fix for a cluster of codes including P1622, particularly on 5.7L models.
   How to confirm: A Chrysler dealership or a qualified repair shop can check the current PCM software version against the latest available version using your vehicle's VIN and a wiTECH scan tool.
   Typical fix: Reprogram (reflash) the PCM with the updated software. The flash process itself takes approximately 3-5 minutes once connected.
   Est. part cost: $0 (software only)
2. Wiring or Connector Issue 🟡 Medium Probability The O2 sensor wiring harness is exposed to heat, moisture, and road debris, which can cause corrosion, melting, or physical damage over time. Water intrusion in a connector, especially after driving through heavy rain or puddles, is a commonly reported trigger. Wires can also get damaged or melted if they are too close to hot exhaust components, especially after aftermarket header installation.
   How to confirm: Visually inspect the O2 sensor wiring and connectors for damage. Use a multimeter to check for a short to power on the reference voltage circuit. A forum user on a related platform reported this code after driving through a large puddle, suggesting water in the connector.
   Typical fix: Repair or replace the damaged section of the wiring harness or clean/replace the corroded connector. Applying dielectric grease to the connector seal can help prevent future water intrusion. Wiring pigtails and repair kits are available.
   Est. part cost: $10-$50
3. Faulty Oxygen (O2) Sensor ⚪ Low Probability While less common for this specific code, an internal short within the O2 sensor itself can cause the reference voltage to read high. This is more likely to be a cause if only one O2 sensor-related code is present and no software updates are available.
   How to confirm: Disconnect the O2 sensor. If the high voltage condition on the reference circuit disappears, the sensor is likely at fault. A tech on a forum noted that the PCM looks for voltage above 3.7V for over 9 seconds to set the code. The issue often implicates the Bank 1 (driver's side) sensors.
   Typical fix: Replace the faulty O2 sensor. Bank 1 (driver's side) is often implicated.
   Est. part cost: $50-$150

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): If a software reflash does not solve the issue and all wiring and sensors have been confirmed to be good, the PCM itself may have an internal hardware failure. This is the most expensive and least likely cause. The appearance of code P0606 alongside P1622 increases the likelihood of a PCM hardware fault.

Diagnosis Steps

1. Check for Technical Service Bulletins (TSBs). Contact a dealer with your VIN to see if PCM software updates #18-073-20, #18-052-15, or #18-084-16 apply to your vehicle. This is the most critical first step.
2. If a software update is available, have the PCM reflashed by a dealer or qualified shop. This is the most likely solution and should be performed before any parts are replaced.
3. If software is up-to-date, use a scan tool to monitor the live data for the O2 sensor reference voltage. Confirm it is reading high (typically above 3.7 volts for more than 9 seconds).
4. Perform a thorough visual inspection of the O2 sensor wiring harnesses and connectors, especially on Bank 1 (driver's side). Look for signs of melting, chafing, corrosion, or water intrusion. Pay close attention to areas near the exhaust manifold and where the harness might be exposed to puddles.
5. Disconnect the upstream O2 sensor on Bank 1 (driver's side). Check the reference voltage on the harness-side connector with the ignition on. If it's still abnormally high, the issue is in the wiring or PCM.
6. If the voltage returns to normal with the sensor disconnected but reads high when reconnected, the O2 sensor has likely failed internally and requires replacement.
7. If water intrusion is suspected, unplug the affected connectors, clean them with electrical contact cleaner, allow them to dry completely, and apply dielectric grease before reconnecting.
8. If all other steps fail, the issue may be a hardware fault within the PCM, which would require replacement.

Parts You'll Likely Need

• Oxygen Sensor (OEM #5149171AB) — This is needed if the sensor itself is confirmed to have an internal short, but it is not the most common cause. This part number is for an upstream sensor common to this platform and supersedes 5149171AA and 68066160AA.
  Trusted brands: Mopar, NTK, Denso, Bosch
  OEM price range: $80-$120
  Aftermarket price range: $50-$90

Related Codes That Often Appear With This One

• P1621 — This is the corresponding code for 'O2 Sensor Reference Voltage Circuit Low'. They often appear in TSBs together, indicating a general instability in the reference voltage circuit that the PCM software update addresses.
• P0300 — Stands for 'Multiple Cylinder Misfire'. An incorrect air-fuel ratio caused by the O2 sensor circuit fault can lead to misfires. This code is explicitly mentioned in the TSBs for the software update.
• P219A — Stands for 'Bank 1 Air-Fuel Ratio Imbalance'. This is a direct consequence of the PCM being unable to trust the O2 sensor readings to properly balance fuel delivery and is also listed in the relevant TSBs.
• P0606 — Stands for 'Internal Control Processor'. This code often accompanies software-related issues, pointing towards a problem within the PCM itself. Its presence strongly reinforces the need to check for a software update.
• U0140 — Stands for 'Lost Communication With Body Control Module'. This indicates a broader communication or electrical issue on the vehicle, which can be related to the PCM fault and is also addressed by the software update in the TSBs.

Technical Service Bulletins (TSBs) & Recalls

• 18-073-20: Addresses P1622 and a long list of other codes, recommending a PCM software update for 2013-2015 models.
• 18-052-15 REV A: Recommends a PCM software update for P1622 and a list of related codes on 2014 models with the 5.7L engine.
• 18-084-16: Supersedes a previous TSB and again points to a software reflash as the solution for a group of codes including P1622.
• 18-052-15: The original bulletin from 2015 advising a PCM reflash for P1622 on 5.7L engines.

Platform-Specific Known Issues

• Multiple TSBs (#18-073-20, #18-052-15 REV A, #18-084-16, #18-052-15) have been issued by Chrysler specifically to address this code via a PCM software update, indicating it's a known issue that is not typically a hardware failure.
• The issue is particularly noted on models equipped with the 5.7L HEMI V8 engine (sales code EZH or EZC).

Mechanic-Grade Diagnostic Values

• P1622 Fault Trigger Condition — expected: Below 3.7 Volts. Failure: The PCM logs code P1622 if the O2 sensor reference voltage circuit remains above 3.7 Volts for more than 9 seconds.
• O2 Sensor Reference Voltage (Chrysler System) — expected: Approximately 2.8V to 3.2V with key on, engine off.. Failure: A reading significantly higher than 3.2V (like the 3.7V+ that triggers the code) indicates a short to power or internal sensor fault. Some Chrysler systems use a 5V bias that should drop when the sensor becomes active; a stuck 5V reading can also indicate a fault.
• O2 Sensor Heater Element Resistance — expected: Between 5 and 20 ohms when cold.. Failure: A reading of infinite resistance (open circuit) or very low resistance (short circuit) indicates a failed heater element within the sensor.

Scan Tool Commands That Help

• wiTECH (or equivalent): PCM Reprogramming/Reflash — This is the primary fix prescribed by multiple TSBs for code P1622. It should be performed before replacing parts. It is critical to maintain a stable battery voltage between 13.2 and 13.5 volts during the entire flash procedure to prevent PCM failure.

Wiring & Ground Locations

• PCM Connector C4 — At the Powertrain Control Module (PCM), which is typically located in the engine bay.. This connector contains the pins for the O2 sensor return circuit. A technician can back-probe these pins to test for voltage directly at the PCM. Specific pins include Pin 32 (DK BLU/DK GRN wire) for the O2 Downstream Return.
• Bank 1 O2 Sensors — Bank 1 is the driver's side of the engine. The code can be related to the upstream (before catalytic converter) or downstream (after catalytic converter) sensor on this bank.. This directs visual inspection and testing to the correct side of the vehicle, saving diagnostic time.
• G901a — A common ground point located at the left front of the engine compartment.. A poor ground at this location can cause a variety of electrical issues, including incorrect voltage readings on sensor circuits. Verifying this ground is clean and tight is a crucial step in diagnosing any electrical fault.

Real Owner Repair Stories

• RamForum.com user report (Dodge Ram, a platform-mate to the Chrysler 300) — Check Engine Light with code P1622 appeared after a week of heavy rain and driving through puddles.
  ❌ Tried (didn't work) Initial check for wires burned on the exhaust headers, which were found to be okay.
  ✅ What actually fixed it The likely cause was identified as water intrusion into one of the O2 sensor connectors on the driver's side. The recommended and successful fix was to unplug the connector, clean it, let it dry completely, apply dielectric grease to the seal, and reconnect it.