P2680

Code

Generic P — Powertrain

Coolant Degassing Valve Control Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 35 EN: 236 RU: 43

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Page language: EN

Causes

Open or shorted wiring/connector on CDV control circuit
Short to battery voltage (B+) on control wire
Corroded, disconnected, or damaged CDV connector
Failed coolant degassing valve (solenoid) or internal short
Blown fuse or faulty relay supplying the circuit
Incorrect installation or coolant contamination of valve

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Poor cooling system venting; persistent air pockets or slow degassing
Extended warm-up time or overheating in some cases
Coolant loss or boiling at the reservoir under load (if degassing impaired)
Possible rough idle or drivability concerns if cooling is affected

What to check

Read freeze frame and live data with a scan tool; confirm P2680 and any related codes
Visually inspect CDV connector, wiring harness and routing for damage, chafing, or contamination
Check related fuses and relays for continuity and correct operation
Backprobe the control circuit and measure voltage while commanding the CDV ON/OFF
Measure CDV coil resistance with the connector disconnected
Perform a bench test of the CDV by applying 12 V briefly and observing valve operation

Signal parameters

Typical CDV coil resistance (vehicle dependent): roughly 5–50 ohms (check service data)
Expected control behavior: ECM usually drives CDV with a low-side switch; when OFF harness may read ~battery voltage, when ON it will be pulled near 0 V
If driven by PWM, frequency commonly low (a few Hz to ~20 Hz) and duty cycle varies with command
Normal current draw: typically 0.1–2.0 A depending on coil resistance
Open-circuit resistance: infinite (OL); short to B+ will show battery voltage present on control pin when valve not energized

Diagnostic algorithm

Verify code and obtain freeze-frame/live data. Note conditions when DTC set (temp, engine run state).
Visual inspection: check CDV connector for corrosion, bent pins, water ingress and secure fit. Repair any obvious damage.
Check fuses/relays that supply the CDV circuit. Replace any blown fuse and retest.
Unplug the CDV connector and measure coil resistance between the valve terminals. Compare to spec. If out of range, replace valve.
With connector disconnected, check for short to battery: measure voltage from CDV control wire to ground. If battery voltage present with key off/on (depending on circuit), suspect short to B+ or fused feed misrouting.
Backprobe the control wire at the connector, command the CDV ON with a scan tool while monitoring voltage. Expected: harness pulled near 0 V (if low-side driver). If voltage stays high, suspect open/short/high-side condition or faulty driver.
Perform a bench power test on the valve: apply 12 V across the coil briefly and confirm mechanical operation (observe plunger movement). Do not apply continuous power for long periods.
Wiggle test harness while monitoring voltage/continuity to detect intermittent faults.
If wiring and valve check good but the ECM output does not change under commanded conditions, test ECM driver circuit per manufacturer procedures or consider ECM replacement after confirming wiring integrity.
After repairs, clear codes and perform a road/cycle test to confirm DTC does not return and cooling system degasses properly.

Likely causes

Wiring break, connector corrosion, or pin pushed out at the CDV
Short to battery voltage at the harness (power feed contacting control wire)
Failed CDV solenoid (open/short or electrically leaky)
Bad ground or blown fuse feeding the circuit
Less likely: internal ECM driver failure

Fault status

⚠️ Status

P2680 — Coolant Degassing Valve Control Circuit High. The PCM/ECM detects an abnormally high voltage on the degassing valve control circuit. Likely causes include a short to battery, open/poor connection, or a faulty valve or driver. Inspect wiring, connectors, valve, and related fuses; verify operation with a scan tool and voltage/continuity checks.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours