All Powertrain Computer DTC Codes — Complete OBD-II Diagnostic Guide (2026)
This comprehensive reference covers every Powertrain Computer diagnostic trouble code (DTC) — 10 codes total. Each code includes what triggers it, common symptoms, step-by-step diagnostic procedures, and repair guidance.
Detailed DTC Code Guides
P0480: The power‑train control module (PCM) has detected a fault in the circuit that powers Cooling Fan 1. The fan may not receive voltage or the control signal may be interrupted, so it may not spin when the engine gets hot.
Find out why your engine’s cooling fan isn’t turning on, what the P0480 code means, and how to fix it. Includes cost estimates, step‑by‑step DIY, emissions...
- Visual inspection for loose connections and obvious damage
- Check fan fuse and relay
- Scan live data for fan command voltage
- ...see all 5 steps →
P0563: The P0563 code tells the power‑train control module that the overall system voltage is higher than the normal range (typically above ~15 V). This usually points to an over‑charging condition, a faulty voltage regulator, or a wiring issue that lets the battery voltage climb too high.
Discover what the P0563 system voltage high code means, why it appears on Toyota, Honda, Ford, and Chevrolet, and how to fix it with a step‑by‑step DIY...
- Check for obvious issues
- Measure battery voltage
- Scan live data for system voltage
- ...see all 5 steps →
P0600: P0600 tells you the power‑train control module can’t reliably talk to other modules over the vehicle’s data bus. The computer detects a broken or noisy serial link and stores the fault.
Learn what P0600 means, why it appears on Toyota, Honda, Ford and Chevy, and how to fix it yourself. Quick steps, parts cost, and emissions impact.
- Visual inspection of connectors and wiring
- Check battery voltage and ground integrity
- Scan for related communication codes
- ...see all 6 steps →
P0601: P0601 tells the power‑train control module that its internal memory checksum failed. In plain English, the computer’s own data didn’t add up, so the PCM can’t trust its stored information. The result is a warning light and possible erratic engine behavior.
Learn what P0601 means, why it appears on Toyota, Honda, Ford and Chevy, and how to fix it fast with a DIY cost guide—under $150 parts, 30‑60 min.
- Visual Inspection of Power & Ground Connections
- Check Battery Voltage and PCM Supply
- Scan for Related Communication Codes
- ...see all 5 steps →
P0603: The P0603 code tells the power‑train control module that its internal Keep‑Alive Memory (KAM) is not functioning correctly. KAM stores short‑term data such as sensor calibrations, idle settings, and fuel‑trim values, so a failure can cause erratic idle, poor fuel trim, or loss of learned parameters.
Learn what the P0603 code means, why the Keep‑Alive Memory fails, and how to fix it. Includes step‑by‑step DIY, cost estimates, vehicle‑specific tips,...
- Inspect PCM Power/Ground Wires, Fuses & Battery
- Read All Stored Codes & Look for Communication Faults
- Check PCM Power Voltage & Ground Resistance
- ...see all 5 steps →
P0604: The power‑train control module (PCM) has detected a fault in its internal RAM. The computer cannot reliably store or retrieve short‑term data, which can cause erratic engine behavior or a complete loss of control.
Learn what the P0604 code means, why it appears on Toyota, Honda, Ford, Chevrolet and more, and how to diagnose and fix it. Includes safety warnings, cost...
- Quick visual inspection
- Verify PCM power and ground
- Scan for related communication codes
- ...see all 6 steps →
P0605: The PCM has detected a problem with the read‑only memory (ROM) inside the control module. In plain terms, the computer can't reliably access its own programming, which may cause intermittent performance issues or a loss of power‑train functions.
Discover what the P0605 code means, why it shows up on Toyota, Honda, Ford, and Chevrolet models, and how to diagnose and repair it yourself with...
- Quick Visual Scan
- Scan for Related Codes
- Verify Power Supply to the PCM
- ...see all 7 steps →
P0606: The P0606 code tells you that the engine control module (ECM) or power‑train control module (PCM) has detected a problem with its internal processor. In plain English, the computer’s brain isn’t functioning correctly, so it can’t manage fuel, spark, or emissions the way it should.
Learn what the P0606 ECM/PCM processor fault means, why it appears on Toyota, Honda, Ford and Chevy, and how to fix it with a step‑by‑step DIY guide plus...
- Visual Inspection
- Check Battery Voltage
- Scan for Related Codes
- ...see all 6 steps →
P1000: The P1000 code tells you that one or more of the OBD‑II self‑tests (monitors) did not finish during the drive cycle. The engine control module (ECM) cannot confirm that the sensor data is reliable, so the check‑engine light stays on.
Learn what the P1000 code means, why monitors fail, and how to fix it on Toyota, Honda, Ford, and Chevrolet. Get step‑by‑step DIY instructions, cost...
- Check for obvious issues
- Verify battery voltage and charging system
- Perform a live data scan of key sensors
- ...see all 5 steps →
P1684: P1684 indicates that the power‑train control module (PCM) detected a sudden drop in battery voltage (typically below ~9 V) or a complete disconnect. The PCM logs the event so it can verify that stored calibrations survive a power loss.
Discover what the P1684 OBD‑II code means, why the battery was disconnected, how to reset it, and step‑by‑step troubleshooting. Includes cost guide, safety...
- Verify Battery Connection
- Check Battery Voltage
- Clear the Code
- ...see all 5 steps →
Understanding Powertrain Computer Codes
Powertrain Computer diagnostic trouble codes are set by your vehicle's onboard computer (ECU/PCM) when it detects a problem in the computer system. Here's what you need to know:
- How codes are triggered: Sensors monitor computer performance. When readings fall outside expected ranges, the ECU stores a DTC and illuminates the check engine light.
- Freeze frame data: When a code is set, the ECU also records engine conditions at that moment. This data helps pinpoint the exact cause.
- Pending vs. confirmed: A code becomes "confirmed" after multiple drive cycles with the same fault. Pending codes may clear on their own.
Tools You'll Need for Diagnosis
- OBD-II scanner — Essential for reading and clearing codes. A basic scanner works for most codes.
- Digital multimeter — For testing sensor voltages, resistance, and continuity.
- Repair manual — Vehicle-specific wiring diagrams and specifications.
- Safety equipment — Gloves, safety glasses, jack stands for under-vehicle work.
When to See a Mechanic
While many computer codes can be diagnosed at home, see a professional if:
- The code is critical severity — driving may cause further damage
- Multiple related codes are present — suggests a deeper systemic issue
- You don't have the tools or experience for the required diagnostic steps
- The repair involves fuel system, exhaust, or catalytic converter work