P2797 on 2022-2023 Chevrolet Bolt EUV: Auxiliary Pump Failure Causes and Fixes

What's Unique About the 2022-2023 Chevrolet BOLT EUV

The 2022-2023 Bolt EUV is prone to this specific failure due to a known manufacturing issue. General Motors issued Technical Service Bulletin (TSB) 21-NA-148, which identifies a "part quality spill" where an out-of-spec soldering process was used on the auxiliary transmission fluid pump's internal motor. This makes the diagnosis highly specific; unlike on other vehicles where wiring or module issues might be more common, on the Bolt EUV, the pump itself is the overwhelming cause. The failure can occur at very low mileage, sometimes within the first few hundred miles of ownership.

Diagnostic Flowchart

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

Symptoms You May Notice

• "Propulsion Power is Reduced" message on the Driver Information Center (DIC).
🎬 Watch: How battery issues can also trigger propulsion power warnings.
• Vehicle speed suddenly limited, often to 30 mph, even when driving at highway speeds.
• Check Engine Light (Malfunction Indicator Lamp) is illuminated.
• Inability to accelerate normally.
• OnStar diagnostic report confirms code P2797.

Most Likely Causes

1. Internal Failure of the Auxiliary Transmission Fluid Pump 🔴 High Probability → Shop Transmission Assembly A known manufacturing defect related to an improper soldering process is documented in GM TSB 21-NA-148. This bulletin explicitly states a "part quality spill" led to defective pumps being installed at the factory.
   How to confirm: A technician will confirm the code with a GM GDS2 scan tool and follow the diagnostic procedure outlined in TSB 21-NA-148, which points directly to pump replacement as the sole correction. The pump motor is not internally serviceable.
   Typical fix: Replace the auxiliary transmission fluid pump with the updated part. This is performed by a certified EV technician at a dealership and is covered under the EV component warranty (8 years / 100,000 miles).
   Est. part cost: $180-$400 (OEM)

Rare But Worth Checking

• Damaged Wiring or Connectors: While the pump is the most common cause on the 2022-2023 models, an older TSB for the 2017 Bolt EV (17-NA-030) noted that damaged wire insulation or corrosion on the pump harness could cause this code. It's a less likely but possible cause that a technician might investigate if a new pump doesn't resolve the issue.
• Hybrid/EV Powertrain Control Module 2 (HPCM2) Fault: → Shop Engine Control Module (ECM) One owner complaint (NHTSA ODI #11544123) mentioned an issue with the Hybrid Control Processor Module. While likely a secondary result of the pump failure, a module fault is a remote possibility that would be diagnosed after ruling out the pump and wiring.
• Cold Weather Operation: A few owners have anecdotally reported the error occurring only in freezing temperatures after a remote start, hypothesizing that the fluid is too viscous 🎬 See how to perform a drive unit fluid maintenance service. for the pump. One user reported being able to clear the code by 'warming up' the system with several hard acceleration/deceleration cycles before power cycling the car. This is not a confirmed cause or recommended fix.

Diagnosis Steps

1. Verify the presence of DTC P2797 (or related codes P2798, P0C2D) using a GM-compliant OBD-II scan tool.
2. Consult TSB 21-NA-148 for the 2022-2023 Bolt EUV/EV.
3. The TSB identifies a known manufacturing defect with the pump and designates pump replacement as the primary corrective action.
4. A technician may use GM's GDS2 software to manually command the auxiliary pump on/off to confirm it is unresponsive, which isolates the fault to the pump itself.
5. Visually inspect the wiring harness and connector for the auxiliary transmission fluid pump for any obvious damage, though this is not the expected cause.
6. Proceed with replacing the transmission fluid pump as per the service procedure outlined in the GM service manual.
🎬 Watch: A professional walkthrough of the Bolt transmission service.
7. After replacement, clear all DTCs and perform a test drive to ensure the fault does not return.

Parts You'll Likely Need

• Auxiliary Transmission Fluid Pump (OEM #25207705) — This is the component identified by GM in TSB 21-NA-148 as having a manufacturing defect causing code P2797. This part number, 25207705, is the latest revision and supersedes previous numbers 25204070, 25202155, and 25200558. Using the latest part number is critical to ensure the revised, non-defective component is installed.
  Trusted brands: ACDelco, GM Genuine Parts
  OEM price range: $185-$300
  Aftermarket price range: Not generally available

Related Codes That Often Appear With This One

• P2798 — This code for 'Auxiliary Transmission Fluid Pump Control Circuit High' is also listed in TSB 21-NA-148 and points to the same faulty pump issue.
• P0C2D — This code for 'Auxiliary Transmission Fluid Pump Control Module Feedback Signal' is also covered by TSB 21-NA-148 and is another indicator of the same pump failure.
• P0AC4 — This generic code for 'Hybrid Powertrain Control Module Requested MIL Illumination' often accompanies more specific codes like P2797 to indicate a fault has been logged in the powertrain system.

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #21-NA-148: Provides diagnostic aid for DTC P2797, P2798, or P0C2D. It identifies a "part quality spill" with the low voltage electric transmission fluid pump due to an "out-of-spec soldering process." It recommends pump replacement and explicitly states the pump motor is not serviceable. The bulletin applies to 2021-2023 Bolt EV and 2022-2023 Bolt EUV models.

Platform-Specific Known Issues

• A known manufacturing defect in the auxiliary transmission fluid pump is the primary cause, as documented in TSB 21-NA-148.
• The failure can occur at very low mileage, with some owners reporting the issue within days and as few as 170 miles after purchasing the vehicle.
• Owner complaints frequently mention a sudden and dangerous reduction in power while driving on the highway.
• Shortages of the replacement pump (P/N 25207705) have been widely reported, sometimes leading to extended repair times of several weeks to over a month. Some owners have pursued lemon law buybacks due to extended downtime.

Mechanic-Grade Diagnostic Values

• Auxiliary Pump Speed Deviation — expected: Less than 500 RPM difference between commanded and actual speed.. Failure: A difference greater than 500 RPM for approximately 4 seconds will set DTC P2797. This data is viewed on a scan tool.
• Pump Power Supply Voltage — expected: 12V ± 0.5V at the pump connector with key on.. Failure: Low or no voltage at the pump connector indicates a wiring or fuse issue upstream from the pump, not a pump failure.

Scan Tool Commands That Help

• GM GDS2 (Global Diagnostic System 2): Module Diagnostics > HPCM-2 (Hybrid Powertrain Control Module 2) > Output Control Functions > Auxiliary Transmission Fluid Pump — This bidirectional control is used to command the pump ON and OFF manually. If the pump does not respond (no noise or vibration from the pump), it confirms the pump has failed, assuming power and ground to the connector are verified.

Wiring & Ground Locations

• Auxiliary Transmission Fluid Pump — Attached to the driver's side of the transmission/drive unit, accessible after removing the front left wheel and wheelhouse liner.. This is the physical location of the component that needs to be tested and replaced.
• Pump Electrical Connector — Connected directly to the auxiliary transmission fluid pump.. This connector is where a technician will test for power, ground, and command signals to differentiate between a failed pump and a wiring/module issue.

Real Owner Repair Stories

• Reddit user maddumpies in r/BoltEV (2023 Chevrolet Bolt with 32,000 miles) — Got the 'reduced propulsion power' error while accelerating from a stop, limiting speed to ~30mph. The error message disappeared after a few seconds, but the check engine light remained on.
  ✅ What actually fixed it The dealer confirmed code P2797 and the pump failure. They replaced the auxiliary transmission fluid pump under warranty. The part was not in stock but was shipped in, and the total repair took one week.
• Reddit user bobfatherx in r/BoltEV (2023 Chevrolet Bolt EUV with 170 miles) — DTC P2797 occurred four days after delivery while driving on low-speed roads. The 30mph speed limit was cleared by turning the car off and on.
  ✅ What actually fixed it The dealer replaced the transmission fluid pump. The part was on backorder, and the vehicle was in for service for approximately 18 days (Sept 21 to Oct 9).
• Reddit user in r/BoltEV (2023 Chevrolet Bolt EUV, purchased new) — Recurring 'Propulsion Reduced' error and P2797 code. The error often appears after city driving but the warning light turns off before it can be shown to a dealer. Power cycling the car temporarily resolves the limp mode.
  ❌ Tried (didn't work) First dealer replaced the pump, but the error returned within days., Second dealer performed a wiring repair, which worked for two months before the error returned., Third dealer performed another unspecified repair, but the error returned in two days.
  ✅ What actually fixed it The issue is unresolved. This story highlights a rare but frustrating edge case where the standard TSB fix (pump replacement) and subsequent wiring repairs did not solve the problem, suggesting a more complex underlying issue like a module fault or intermittent connection.