Universal Diesel P0670: Glow Plug Control Module Diagnosis
P-code P0670 (FMI N/A) — Glow Plug Control Module A Control Circuit/Open
Quick Answer
On Universal Diesel, P0670 means Glow Plug Control Module A Control Circuit/Open. Prove the system with live data on Diesel Laptops before replacing parts.
Overview: Universal Diesel P-code P0670
On Universal Diesel, P0670 means Glow Plug Control Module A Control Circuit/Open. Prove the system with live data on Diesel Laptops before replacing parts. This page covers symptoms, causes, tests, and common misdiagnoses.
Repair Snapshot
Time
1 - 3 Hours
Difficulty
Intermediate
Parts Cost
$40 - $1,200
Dealer Labor
$300+
Tools Required
- Diesel Laptops
- Jaltest
- Multimeter
What P-code P0670 Means
P0670 on Universal Diesel reports Glow Plug Control Module A Control Circuit/Open. Typical root causes include wiring faults, sensor rationality issues, and mechanical problems in the electrical path. Use Diesel Laptops / Jaltest to confirm before a parts cannon.
Symptoms Drivers Notice
- Malfunction indicator lamp illuminated
- Power loss, rough running, or limp mode under load
- Related aftertreatment or fuel-system complaints depending on code family
- Code returns after clearing if root cause remains
Most Likely Root Causes
Common Misdiagnoses (Don't Waste Parts)
Why it happens:
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Why it happens:
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Why it happens:
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Master Tech Commentary
Mechanic's Notes
Shop tip (Universal Diesel P0670): Do not quote the expensive assembly from the code name alone. Confirm live data rationality and wiring first.
Step-by-Step Diagnostic Procedure
- Step 1: Scan with Diesel Laptops and save freeze-frame for P0670.
- Step 2: Inspect connectors and harness for the glow plug control module.
- Step 3: Compare PID values to mechanical gauges or known-good ranges.
- Step 4: Repair the proven fault, then verify with a loaded drive cycle.
Live Data & Freeze-Frame Tips
Log the PIDs tied to P0670 under freeze-frame load with Diesel Laptops. Compare commanded vs actual values.
When to Limp In vs Tow
Drive carefully if power remains controllable; tow if limp mode is severe.
Related Fault Codes
Frequently Asked Questions
What does P0670 mean on Universal Diesel?
Glow Plug Control Module A Control Circuit/Open. Confirm with live data before replacing parts.
Can I drive with P0670?
Short trips may be possible, but continued hard pulls risk limp mode or aftertreatment damage. Diagnose promptly.
What tools should I use?
Diesel Laptops, Jaltest, Multimeter.
Should I clear the code first?
No — save freeze-frame and repair first.
More Universal Diesel codes on this system
- Universal Diesel P-Code P0402 — EGR Excessive Flow Detected
- Universal Diesel P-Code P0404 — EGR Circuit Range/Performance
- Universal Diesel P-Code P0473 — Exhaust Pressure Sensor High
- Universal Diesel P-Code P0671 — Glow Plug Circuit Cylinder 1
- Universal Diesel P-Code P0522 — Engine Oil Pressure Sensor Circuit Low
- Universal Diesel P-Code P0500 — Vehicle Speed Sensor Malfunction
- Universal Diesel P-Code P0638 — Throttle Actuator Control Range/Performance
- Universal Diesel P-code P0401 — EGR Insufficient Flow
Guides that go deeper
- Power Stroke 6.7 Glow Plug Codes: Diagnose Before Replacing the Harness
6.7 Power Stroke glow plug and module codes often start as open circuits or harness chafe. Test plugs and control side before a full harness R&R.
- DEF in the Diesel Tank (or Diesel in the DEF Tank): Damage Control Steps
Do not start the engine. DEF is 32.5% urea in water and corrodes fuel system metals; diesel destroys SCR catalyst coating and doser seals. Cranking converts a drain-and-flush job into a fuel system or aftertreatment replacement.
- J1939 Datalink Faults: Diagnosing CAN Bus Errors Without Guessing
SPN 639 means the J1939 datalink itself is failing, not the component named in the code. Measure termination resistance and bus voltage before replacing any module — most datalink faults are wiring, connectors, or a single noisy node.