P240C

Code

Generic P — Powertrain

EVAP System Leak Detection Pump Heater Control Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 38 EN: 81 RU: 41

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Page language: EN

Causes

Short to battery voltage (wiring or connector)
Open or high-resistance wiring/connector in heater circuit
Corroded or damaged pump connector or terminals
Failed leak detection pump heater element (internal short/open)
Blown fuse or faulty relay feeding the EVAP pump circuit
Poor ground or chassis ground connection

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
EVAP system test cannot run or fails
EVAP-related fault codes stored (P240C and possibly others)
Possible increased evaporative emissions; may fail emissions test
Usually no drivability change, but EVAP system may be disabled

What to check

Read freeze frame and stored data with a scan tool; note battery voltage and operating conditions when code set
Visual inspection of EVAP pump, harness, and connectors for damage, corrosion, or water intrusion
Check relevant fuses and relays for the EVAP/leak detection pump circuit
Backprobe/measure voltage at the pump connector with ignition ON (engine OFF) and while commanded ON/OFF using scan tool
Disconnect pump module and measure heater element resistance with DMM
Perform continuity and short-to-B+ and short-to-ground checks on control and power wires

Signal parameters

Battery voltage (system) with key ON: ~11–14.5 V
Control circuit voltage when PCM commands heater ON: near 0–1.0 V (PCM typically grounds the circuit)
Control circuit voltage when PCM commands heater OFF: near battery voltage (11–14.5 V)
Heater element DC resistance (typical range, vehicle-dependent): low ohms — often a few ohms up to a few tens of ohms (measure on vehicle-specific service data)
Heater current when energized: typically under 5 A (vehicle-dependent)
A steady high voltage on the control pin when the PCM expects to see low indicates a high/short-to-B+ or open/float condition

Diagnostic algorithm

Verify the code and any related EVAP/engine codes. Record freeze frame and test conditions.
Inspect visually: check the EVAP pump, wiring harness, connectors, and chassis grounds for damage, corrosion, or moisture.
Check fuses and relays that supply the EVAP pump circuit; replace if faulty.
With ignition ON (engine OFF), backprobe the EVAP pump heater connector. With no command, the control pin should be near battery voltage; command the pump ON with a scan tool and observe voltage should go low (near 0 V) if PCM is grounding the circuit.
If control pin is high when PCM commands ON, disconnect the pump and measure resistance of the heater element at the pump side. Compare to vehicle spec. An open or unexpected value indicates a faulty pump.
Check continuity between the PCM control pin and the pump connector. Look for short-to-B+ on the control wire (voltage present when circuit should be low) and short-to-ground on the power feed if applicable.
Check for poor or missing ground points that could cause incorrect voltage readings.
If wiring and pump check good, backprobe the PCM control output. If the PCM does not switch the output as commanded or shows abnormal voltages, consider PCM driver failure — confirm with an oscilloscope or substitute PCM only after all wiring components are proven good.
Repair or replace damaged wiring, connector, fuse/relay, or pump as needed. After repair, clear codes, perform the EVAP system test/cycle per service manual, and verify code does not return and readiness is restored.
If intermittent, perform extended monitoring or wiggle testing while monitoring live data or voltage to capture condition.

Likely causes

Wiring shorted to B+ at or near leak detection pump connector
Disconnected or corroded connector causing intermittent high reading
Internal shorted heater element inside the leak detection pump module
Faulty fuse/relay that has altered circuit behavior
PCM/ECM driver transistor failed (less common)

Fault status

⚠️ Status

EVAP leak detection pump heater control circuit voltage higher than expected (control circuit high). Check pump, wiring/connector, fuses/relays, and PCM output.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours