What Does P240B Mean?
The leak detection pump heater control circuit voltage is lower than expected. This indicates a short to ground, excessive current draw, or PCM driver circuit problem.
Common Causes
40%
Short to ground in heater control circuit wiring
30%
Internal short in leak detection pump heater element
15%
Damaged connector causing ground short
10%
PCM heater driver circuit shorted internally
5%
Excessive resistance causing voltage drop
Diagnostic Steps
1
Step 1: Disconnect leak detection pump heater connector and check for voltage short to ground on control wire
2
Step 2: Measure heater element resistance; very low resistance indicates internal short
3
Step 3: Inspect wiring harness for pinch points, damage, or routing near sharp edges causing ground shorts
4
Step 4: Check PCM connector terminals for corrosion or damage on heater control circuit pins
5
Step 5: If wiring tests good and heater resistance is too low, replace leak detection pump
Estimated Repair Cost
$150 - $700
Parts + labor, varies by vehicle and location
The leak detection pump heater control circuit voltage is lower than expected. This indicates a short to ground, excessive current draw, or PCM driver circuit problem.
The most common cause of P240B (Evaporative Emission System Leak Detection Pump Heater Control Circuit Low) is: Short to ground in heater control circuit wiring
Typical repair costs for P240B range from $150 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive. Short circuit may blow fuses repeatedly but poses no immediate safety risk.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P240B to identify the root cause.
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Quick Info
Category
Powertrain
System
Evaporative Emissions System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
