P2797 on 2017-2019 Chrysler Pacifica Hybrid: Auxiliary Pump Causes and Fixes

What's Unique About the 2017-2019 Chrysler PACIFICA

The P2797 code on a Chrysler Pacifica is almost exclusively an issue for the Hybrid model. Its e-Flite Si-EVT transmission relies on 🎬 Watch: A deep dive into how the Si-EVT transaxle works. a 3-phase auxiliary electric oil pump to maintain hydraulic pressure and fluid circulation when the gasoline engine isn't running. This is different from the non-hybrid model's conventional ZF 9-speed automatic transmission. The presence of this code often points to issues addressed by Chrysler through Technical Service Bulletins (TSBs), which may involve software updates to the Hybrid Control Processor (HCP) and Power Inverter Module (PIM) rather than immediate hardware replacement.

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 or Malfunction Indicator Lamp (MIL) is on
• "Service Transmission" warning message on the dash
• "Service Hybrid System" or "Propulsion System Warning" message.
• Vehicle may not enter or stay in electric-only (EV) mode
• Delayed, harsh, or missed gear shifting.
• Reduced acceleration or feeling of power loss, vehicle may be in 'limp mode'.
• Inability to pass a state smog check due to permanent fault codes.
• Vehicle may not move from a stop.

Most Likely Causes

1. Software Glitch in Control Modules 🔴 High Probability Multiple TSBs (08-114-22, 08-010-21, 08-013-21) have been issued by Chrysler for a range of DTCs, including P2797, that can be resolved by flashing the Hybrid Control Processor (HCP) and Power Inverter Module (PIM) with updated software. These updates address incorrect fault detection logic and can prevent the setting of permanent fault codes that fail emissions tests.
   How to confirm: A Chrysler dealership or a qualified shop with access to OEM software (wiTECH) can check if the vehicle's control modules have the latest updates by referencing the TSBs against the vehicle's VIN.
   Typical fix: Flashing/reprogramming the relevant control modules (HCP, AHCP/PIM, PCM) to the latest software version as specified in the TSBs.
   Est. part cost: $0
2. Damaged Wiring Harness or Connectors 🟡 Medium Probability A GM bulletin for a similar issue (which later added P2797) notes that the pump's wiring harness can become damaged or corroded from rubbing against other components, leading to a short or open circuit. Pacifica Hybrid models have also been subject to recalls and TSBs for wiring harness issues inside the transmission.
   How to confirm: Visually inspect the wiring harness leading to the auxiliary transmission fluid pump for signs of chafing, corrosion, or loose connections. Access often requires removing the front left wheel and wheelhouse liner. Check for voltage and ground at the pump connector with the ignition on.
   Typical fix: Repairing the damaged section of the wire and re-securing the harness away from any contact points using electrical tape. In severe cases, the harness may need replacement.
   Est. part cost: $5-$50
3. Failed Auxiliary Transmission Fluid Pump 🟡 Medium Probability The electric pump motor can fail internally over time due to wear, fluid contamination, or electrical faults within the motor windings. This is the most likely cause after software and wiring have been ruled out.
   How to confirm: After ruling out software and wiring, a technician can use a diagnostic scan tool to command the pump to activate and monitor its response and pressure readings. If it fails to activate or meet pressure specifications (e.g., greater than 145 kPa / 21 psi in some applications), the pump is likely faulty. A diagnostic on a similar system for a GM vehicle specifies that the actual pump speed should be within 10% of the commanded speed.
   Typical fix: Replacement of the auxiliary transmission fluid pump assembly.
   Est. part cost: $150-$500
4. Faulty Control Module (PIM) ⚪ Low Probability While less common, the control module that commands the pump (the Power Inverter Module, or PIM) can fail internally. This is often a diagnosis of exclusion.
   How to confirm: This is typically diagnosed by exclusion. If the pump, wiring, and software are all confirmed to be good, the control module becomes the primary suspect. This requires advanced diagnostics to confirm the module is sending the command signal.
   Typical fix: Replacement and programming of the faulty Power Inverter Module (PIM).
   Est. part cost: $400-$1000

Diagnosis Steps

1. Scan the vehicle for all DTCs. Note any other codes that appear alongside P2797, as they can provide important clues (e.g., codes mentioned in TSBs).
2. Check for applicable Technical Service Bulletins (TSBs) for your vehicle's VIN. Specifically, inquire about TSBs 08-114-22, 08-010-21, and 08-013-21. If available and applicable, have the relevant control modules updated first.
3. If software is up to date, perform a thorough visual inspection of the wiring harness and electrical connector for the auxiliary transmission fluid pump. Access requires removing the front left wheel and wheelhouse liner. Look for chafing, corrosion, or loose pins.
4. Using a capable scan tool (like OEM wiTECH), attempt to command the auxiliary pump ON and monitor its status and related data PIDs (e.g., pump speed, pressure). The actual pump speed should stay within 10% of the commanded speed.
5. If the pump does not respond and the wiring is intact, test for power (should be ~12V) and ground at the pump's electrical connector to verify the integrity of the circuit.
6. If the pump has power and ground but does not operate or fails to build pressure, the pump itself has likely failed and requires replacement.
7. If the pump and wiring are good, the issue may lie with the controlling module (PIM), which requires more advanced diagnostics, such as checking the PWM command signal from the module.

Parts You'll Likely Need

• Auxiliary Transmission Fluid Pump (OEM #68237837AA) — This is the component identified by the code. If it fails internally, it must be replaced. This is a common failure point after software and wiring issues are ruled out. Note: This part number is for an auxiliary pump on the Pacifica, but it is listed as a coolant pump by some vendors; always verify the exact transmission pump part number with a dealer using your VIN.
  Trusted brands: Mopar
  OEM price range: $200-$500
  Aftermarket price range: $150-$350

Related Codes That Often Appear With This One

• P0CF3 — TSB #08-114-22 and #08-013-21 list P2797 and P0CF3 ('Control Pilot Circuit Open') together, indicating a software update may resolve both.
• P06E4 — TSB #08-010-21 groups P2797 with P06E4 ('Control Module Wake-Up Circuit Performance'), suggesting a related software or module communication issue.
• P07B5 — Also listed in TSB #08-010-21, pointing to a potential software calibration issue affecting multiple transmission-related sensors and actuators.
• P2798 — This code indicates 'Auxiliary Transmission Fluid Pump Control Circuit Low', pointing specifically to an electrical circuit problem (like a short to ground) with the same pump, often related to a damaged harness.

Technical Service Bulletins (TSBs) & Recalls

• 08-114-22: Addresses MIL illumination with P2797 and other codes, related to the Hybrid Propulsion System. This TSB supersedes 08-013-21 and involves reprogramming the HCP and AHCP (PIM) with updated software.
• 08-010-21: Addresses MIL illumination and smog check failures due to permanent codes like P2797, fixed by a software update for multiple modules.
• 08-013-21: An earlier TSB, now superseded by 08-114-22, that addressed MIL illumination with P2797 and other codes with a powertrain module software update.

Platform-Specific Known Issues

• Chrysler has issued multiple TSBs that address P2797 among other codes. These bulletins often point to a software update for the Hybrid Control Processor (HCP) or other modules as the fix.
• TSB #08-114-22, #08-010-21, and #08-013-21 all list P2797-00 'Auxiliary Transmission Fluid Pump Performance' as a code that may be resolved with a software flash.
• Owners on forums frequently report that a software update at the dealership resolves this code, especially when it appears with other TSB-related codes.

Mechanic-Grade Diagnostic Values

• Auxiliary Pump Speed vs. Commanded Speed — expected: Actual pump speed should be maintained within 10% of the commanded speed via scan tool.. Failure: Actual speed deviates by more than 10%, the pump makes excessive noise, or stalls.
• Auxiliary Pump Motor Winding Resistance — expected: While specific values for the Pacifica were not found, a similar system on a Toyota hybrid specifies a resistance of 151 to 203 Ω between certain terminals of the pump relay.. Failure: Resistance outside the specified range would indicate a faulty pump motor or relay.

Hidden / Shadow Codes Worth Checking

• Permanent DTC (PDTC): P2797 can be stored as a Permanent DTC, which cannot be cleared by a standard scan tool 'erase codes' function or by disconnecting the battery. The vehicle's computer must verify that the repair has been successfully completed through a series of specific drive cycles before it will clear the code itself. (see via A scan tool that specifically supports reading Permanent DTCs is required. Many affordable modern scanners have this function.)

Scan Tool Commands That Help

• wiTECH (Chrysler OEM) or equivalent advanced scan tool: Auxiliary Transmission Fluid Pump activation / speed command — This bidirectional control is essential for diagnosis. It allows a technician to command the pump to turn on (e.g., to 50% speed) and monitor its actual speed and pressure response to determine if the pump is physically working, independent of the vehicle's automatic commands.
• wiTECH or equivalent: Read/Clear DTCs in HCP and AHCP/PIM — Used to check for related codes and to clear faults after a repair. Note that if P2797 is set as a permanent code, it cannot be cleared this way and requires a specific drive cycle to be extinguished by the ECU.

Wiring & Ground Locations

• Auxiliary Pump Drain Plug — On the bottom of the transaxle, closer to the driver's side. It is near the engine oil drain plug and requires an 8mm Allen key.. While not an electrical component, knowing its location is critical for the first step of a physical pump replacement, which involves draining the transmission fluid.
• Transmission Assembly Harness Connector — The main external connector on the transmission assembly case.. This is a primary test point for checking resistance of internal solenoids and wiring without removing the transmission. A diagnostic document for the non-hybrid Pacifica shows using this connector to test solenoid resistance.

Real Owner Repair Stories

• Reddit user on r/MechanicAdvice (2018 Chrysler Pacifica Hybrid) — Check engine light on, car would not charge, failed emissions test for code P1C5E. After a dealership visit, the light remained on.
  ❌ Tried (didn't work) Replacing the 12V engine battery, which tested low on CCA but did not resolve the issue.
  ✅ What actually fixed it The user was advised that the symptoms and multiple codes (including P2797, P06E4, P07B5) pointed directly to Technical Service Bulletin #08-010-21, which requires a software flash of the Hybrid Control Processor (HCP) and other modules. The final fix was having the dealership perform the TSB software update.

OEM Part Supersession History

• 68237837AA → 68643461AA — Part number was updated for vehicles built on or after July 29, 2023.
  Heads up: The part is listed as an 'Auxiliary Coolant Pump' by Mopar, which can cause confusion. It is critical to verify the correct part number for the auxiliary *transmission* pump with a dealer using the vehicle's VIN, as the same part number appears to be used for different systems in parts catalogs.

Model Year Variations Within This Range

• 2017-2019: The Pacifica Hybrid uses a specific e-Flite Si-EVT transaxle, which is completely different from the ZF 9-speed automatic transmission used in the non-hybrid gasoline models. Therefore, code P2797 and its diagnosis are exclusive to the Hybrid model.