P0603 on 2018-2021 Nissan KICKS: Keep Alive Memory (KAM) Error Causes and Fixes

What's Unique About the 2018-2021 Nissan KICKS

Modern, electronics-heavy vehicles like the Nissan KICKS are particularly sensitive to battery voltage fluctuations. The P0603 code is frequently the very first symptom of a weakening battery, often appearing before any noticeable starting issues. Nissan has issued multiple Technical Service Bulletins (TSBs) for this exact code across a wide range of models, confirming it's a common, fleet-wide issue and guiding technicians to check the battery first. Specifically, TSB NTB16-018D states that P0603 is often the result of the battery voltage dropping below 11 volts with the ignition on. For KICKS owners, this code is more often a simple battery health indicator than a sign of a complex ECM failure.

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 or unstable idle
• Hesitation during acceleration
• Reduced fuel economy
• Harsh or unusual transmission shifting behavior
• Difficulty starting the engine
• Engine stalling

Most Likely Causes

1. Weak or Failing Battery 🔴 High Probability → Shop Vehicle Battery Nissan TSBs NTB16-018d and NTB21-027, along with general vehicle sensitivity, point to low battery voltage as the primary trigger. 🎬 Watch: A mechanic explains common causes and fixes for P0603. The system is sensitive to voltage drops below 11V with the ignition on, a condition explicitly mentioned in TSB NTB16-018D.
   How to confirm: Use a multimeter to test the battery. A healthy battery should read about 12.6V with the engine off and 13.5-14.5V with the engine running. A definitive load test, often offered for free at auto parts stores, is recommended as a simple voltage check may not be sufficient.
   Typical fix: Replace the vehicle's battery. The original battery is often an EFB (Enhanced Flooded Battery), and replacement with an EFB or AGM (Absorbed Glass Mat) battery is recommended.
   Est. part cost: $150-$250
2. Loose or Corroded Battery Terminals 🔴 High Probability → Shop Vehicle Battery Corrosion or a loose connection can interrupt the constant power supply to the ECM, even if the battery itself is healthy. This is a common issue on all vehicles and a primary check for P0603.
   How to confirm: Visually inspect the battery terminals and cables for white or greenish buildup (corrosion) and ensure the cable clamps are tight and cannot be moved by hand.
   Typical fix: Disconnect the battery (negative terminal first), clean the terminals and clamps with a wire brush and a baking soda/water solution, then reconnect securely (positive terminal first).
   Est. part cost: $1-$10
3. Recent Battery Disconnection or Replacement 🟡 Medium Probability → Shop Vehicle Battery Intentionally disconnecting the battery for service will cut power to the ECM and set this code. It's an expected outcome, not a sign of a fault.
   How to confirm: If the battery was recently replaced or disconnected for any reason, this is the likely cause.
   Typical fix: Clear the code with an OBD-II scanner. If there are no other issues, it should not return. Following the ignition cycle procedure in TSB NTB16-018D (turning ignition on for 1 sec, off for 10 sec, repeated 10 times) can confirm the fix.
   Est. part cost: $0

Rare But Worth Checking

• Failing Alternator: → Shop Alternator A faulty alternator won't charge the battery correctly, leading to low system voltage that triggers P0603. This is usually accompanied by a battery warning light or dimming headlights. A charging voltage check should show 13.5-14.5V.
• Blown Fuse or Wiring Issue: A blown fuse for the ECM's memory circuit or a damaged/loose ground wire can cut off the keep-alive power. A poor ground connection under the dash was the culprit in one documented case for a similar Nissan vehicle.
• Faulty Engine Control Module (ECM): → Shop Engine Control Module (ECM) This is the least likely cause. All power and ground-related issues must be exhaustively ruled out before condemning the ECM. The provided TSB NTB21-027 does mention a potential EEPROM issue that could require dealer intervention, but still directs battery testing as the first step.

Diagnosis Steps

1. Check if the battery was recently disconnected or replaced. If so, clear the code and perform the ignition cycle procedure outlined in TSB NTB16-018D: Turn ignition ON for 1 second, then OFF for 10 seconds. Repeat 10 times. 🎬 See how to perform this ECM reset procedure step-by-step. If the code does not return, the issue is resolved.
2. Visually inspect the battery terminals for corrosion and ensure the connections are clean and tight.
3. Perform a battery load test using a professional tester. A simple voltage check may not be sufficient. Replace the battery if it fails the load test.
4. With the engine running, use a multimeter to check the alternator's output voltage at the battery terminals. It should be stable and between 13.5V and 14.5V.
5. Inspect fuses related to the ECM's power supply. The passenger compartment fuse box is located under the dashboard on the driver's side.
6. Check main ECM and body ground connections for tightness and cleanliness. A poor ground can mimic a low voltage situation. A 2018 Kicks wiring diagram shows ECM grounds at pins 157, 159, and 162 of connector E19.
7. If all the above steps do not resolve the issue, consult the dealer. The problem could be related to an ECM software update as suggested by TSB NTB21-027.

Parts You'll Likely Need

• Automotive Battery — A weak or failing battery is the most frequent cause of a P0603 code on this vehicle. The OEM battery is typically a Group Size 47 or H5, often an EFB (Enhanced Flooded Battery) type.
  Trusted brands: Interstate (MTX-47/H5), Duralast (H9-AGM), Bosch (51744KCHJ), NAPA The Legend (BAT 9847)
  OEM price range: $200-$300
  Aftermarket price range: $150-$250
• Battery Terminal Cleaner — Used to remove corrosion from battery posts and cable clamps, which restores the electrical connection to the ECM.
  Trusted brands: CRC, NOCO, Permatex
  OEM price range: $5-$15
  Aftermarket price range: $3-$10

Related Codes That Often Appear With This One

• P062F — Nissan TSB NTB21-027 explicitly states that P0603 and P062F (EEPROM Error) can be stored together, indicating a potential software or internal module memory issue, often triggered by low battery voltage during startup.

Technical Service Bulletins (TSBs) & Recalls

• NTB21-027: MIL ON WITH DTC P062F AND/OR P0603 STORED
• NTB16-018d: MIL ON WITH P0603 STORED FOR ECM BACK UP CIRCUIT

Platform-Specific Known Issues

• Nissan has issued Technical Service Bulletin NTB21-027, which notes that on some 2018 models, P0603 may be stored along with P062F (EEPROM), potentially indicating a need for dealer-level diagnostics after confirming the battery is healthy.
• TSB NTB16-018d (a revision of NTB16-018c) addresses P0603 specifically as an 'ECM BACK UP CIRCUIT' fault and emphasizes that it is often the result of low battery voltage (below 11V), a discharged battery, or battery terminal disconnections. It provides a specific 10-cycle ignition test to confirm the fix.

Mechanic-Grade Diagnostic Values

• Battery Voltage (Keep Alive Power Check) — expected: 11 volts or more. Failure: Less than 11 volts indicates insufficient power to maintain ECM memory, which will trigger P0603.
• ECM Power and Ground Voltage Drop — expected: Less than 0.5 volts. Failure: A voltage drop greater than 0.5V on either the power or ground side of the ECM circuit indicates high resistance that can cause memory loss.

Scan Tool Commands That Help

• Nissan CONSULT-III Plus: Erase DTCs — This is the dealer-level tool used to clear fault codes before performing the ignition cycle confirmation test as per TSB NTB16-018D.
• Manual Procedure: Ignition Cycle Confirmation Test — After clearing the code and ensuring battery voltage is good, this procedure is used to verify the fix. Turn ignition ON for 1 second, then OFF for 10 seconds. Repeat 10 times. If P0603 does not return, the fix is confirmed.
• Manual Procedure: IPDM Auto-Active Test (Self-Test) — To quickly verify the functionality of the Intelligent Power Distribution Module and its outputs (lights, horn, fans). While not specific to P0603, it can help rule out broader electrical issues. It is initiated by pressing the driver's door jamb switch 10 times.

Wiring & Ground Locations

• ECM Connector E19 — At the Engine Control Module (ECM) in the engine bay.. This connector contains the primary power and ground pins for the ECM. A 2018 wiring diagram shows the constant power supply is at pin 155, and crucial grounds are at pins 157, 159, and 162. Testing voltage and ground integrity at these specific pins is a key diagnostic step.
• Body Ground Connections — Multiple locations, but a key area to check is under the driver's side dashboard near the steering column.. A loose or forgotten body ground can interrupt the ECM's circuit, causing a P0603. One documented fix for this code on a similar Nissan involved finding and re-securing a ground bolt in this area that was left loose after a prior repair.
• Passenger Compartment Fuse Box — Located under the dashboard, typically to the left of the steering column on the driver's side.. This fuse box contains fuses for various interior and control circuits. The fuse that provides the constant 'keep-alive' power to the ECM may be located here.

Real Owner Repair Stories

• YouTube channel 'rustbucketvalleygarage' (Nissan Versa (shares platform/engine with Kicks)) — Check Engine Light with code P0603 after the car was sitting for a while.
  ❌ Tried (didn't work) The owner had installed a battery disconnect switch, fearing a parasitic drain, which was the source of the problem.
  ✅ What actually fixed it Removing the aftermarket battery disconnect switch and ensuring the battery remained connected at all times resolved the code after it was cleared.
• YouTube channel 'Henryboy Tv vlog' (Nissan Pathfinder) — Check Engine Light with code P0603.
  ❌ Tried (didn't work) Initial checks of the battery and main engine grounds did not reveal the problem.
  ✅ What actually fixed it The technician found a body ground wire under the dashboard that had not been reconnected during a previous repair. Securing this ground bolt fixed the issue.

OEM Part Supersession History

• 23703-5RL0A → N/A - Appears specific to early models — Model Year Part
  Heads up: This part number is listed for 2018-2019 Nissan Kicks models.
• 23703-5EA0A → N/A - Appears specific to later models — Model Year Part
  Heads up: This part number is listed for 2020-2021+ Nissan Kicks models. Replacement ECMs are sold 'blank' and require programming by a dealer or specialist with Nissan's CONSULT software. A used module cannot be swapped without reprogramming.

Model Year Variations Within This Range

• 2018-2019 vs 2020-2021: The OEM part number for the Engine Control Module (ECM) is different. Early models (2018-2019) may use part number 23703-5RL0A, while later models (2020-2021) use 23703-5EA0A. It is critical to verify the correct part number for the specific vehicle before ordering a replacement.