← View Generic P0840 Guide Severity: Medium
🚗 Vehicle-Specific Guide

This guide is customized for your 2021 Honda PASSPORT

P0840: P0840: Transmission Control Module (TCM) Range/Performance Problem

on 2021 Honda PASSPORT

Fix Cost
$200 - $1000
Parts & Labor
Difficulty
3/5
1-2 hours
DIY Possible?
❌ No
Pro recommended
Your Vehicle
2021 Honda
PASSPORT
⚠️

Important for 2021 Honda PASSPORT Owners

Before starting repairs, verify which engine your 2021 Honda PASSPORT has. Check your VIN or engine code to ensure you order the correct parts.

📖 What Does P0840 Mean on 2021 Honda PASSPORT?

The TCM has detected a problem with the transmission's range and performance, which can cause issues with gear shifting and transmission operation.
⚠️

Symptoms

  • • Transmission slips
  • • hesitates
  • • or refuses to engage gears
  • • unusual noises
  • • or vibrations while driving
🔍

Common Causes

  • • Faulty transmission solenoid
  • • faulty transmission pressure sensor
  • • faulty TCM
  • • clogged transmission filter
  • • low transmission fluid level
🛠️

How to Fix P0840 on 2021 Honda PASSPORT

1. Check transmission fluid level and condition, 2. Scan for any other trouble codes, 3. Test transmission solenoids and pressure sensor, 4. Replace faulty components, 5. Update TCM software if necessary

🔧

Need Maintenance Info for Your PASSPORT?

Get oil capacity, filter specs, and torque settings for your specific 2021 Honda PASSPORT.

View 2021 Honda PASSPORT Specs

Parts for 2021 Honda PASSPORT

Transmission solenoid Shop ↗ Transmission pressure sensor Shop ↗ Transmission filter Shop ↗ Transmission fluid Shop ↗

Essential Tool

Must Have

OBD2 Scanner

Read & clear codes on your 2021 Honda PASSPORT

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Related Diagnostic Codes

Other codes that may appear with P0840

P0838 Sequential Code

P0838: Transmission Control Module (TCM) Range/Performance Problem

Medium
P0839 Sequential Code

P0839: Transmission Control Module (TCM) Range/Performance Problem

Medium
P0841 Sequential Code

P0841: Transmission Control Module (TCM) Range/Performance Problem

Medium
P0842 Sequential Code

P0842: Transmission Control Module (TCM) Range/Performance Problem

Medium

💡 Why These Codes Are Related:

  • • Similar Issues: Same root cause or component failure
  • • Related Problems: Often occur together due to system interactions
  • • Sequential Codes: Progressive failure stages or multiple sensors
  • • Same System: Components within the same automotive system