P240B — Evaporative Emission System Leak Detection Pump Heater Control Circuit Low

powertrain (engine/transmission)

Is it safe to drive?

Short-term driving is OK Safe to drive. EVAP faults affect emissions, not drivability — you can keep using the car while planning the repair. Fuel vapour smell is a reason to fix it sooner: vapours are flammable and harmful.

How to diagnose with an OBD scanner

  1. Read the code and freeze frame Connect an OBD2 scanner, confirm P240B is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
  2. Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
  3. Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the evaporative emission (EVAP) system for damage, corrosion, chafing or poor contact.
  4. Subsystem check Check for supply voltage at the evaporative emission system leak detection pump heater control connector first; then measure resistance from the signal wire to ground — near-zero ohms confirms a short to ground in the harness.
  5. Subsystem check Check the fuel cap first — it is the most common cause; inspect the seal and tighten until it clicks.
  6. Subsystem check Run an EVAP leak test (smoke test) to locate small leaks in hoses, canister and valves.
  7. Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P240B does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P240B (parts and labor, USD, independent shop rates): Replace the fuel cap: $20–$60; Replace the purge or vent valve: $120–$350; Replace the charcoal canister: $250–$700. Overall, fixing P240B usually costs between $20 and $700. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

How much does it cost to fix P240B?

Replace the fuel cap — $20–$60; Replace the purge or vent valve — $120–$350; Replace the charcoal canister — $250–$700. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What are the symptoms of P240B?

Drivers most often notice: no noticeable driving symptoms in most cases, fuel smell near the car, especially after refueling, difficulty refueling (nozzle clicks off), slightly worse fuel economy.

Will P240B clear itself?

Sometimes P240B clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What is the most common cause of P240B?

The most common causes are: cracked EVAP hoses or lines, saturated or damaged charcoal canister, faulty vent valve or leak detection pump.

How do I diagnose P240B myself?

Start with a scan: confirm P240B, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the evaporative emission system leak detection pump heater control, and verify the suspect component against live data before buying parts.

What does P240B mean?

The engine control module sets P240B when it detects a fault in the evaporative emission (EVAP) system. In practical terms: evaporative emission system leak detection pump heater control circuit low. The code belongs to the powertrain (engine/transmission) group of OBD2 codes.

“Circuit low” means the voltage on the evaporative emission system leak detection pump heater control circuit stays below the expected minimum — close to ground. The usual physical reasons are a short to ground, a chafed wire touching metal, a missing supply voltage, or a failed component dragging the signal down.

To set P240B, the control module compares live readings of the evaporative emission (EVAP) system against calibrated limits, usually over several drive cycles. Alongside the code it stores a freeze frame — a snapshot of rpm, load, coolant temperature and vehicle speed at the moment of failure. Reading that snapshot first saves diagnostic time.

Common symptoms of P240B

  • no noticeable driving symptoms in most cases
  • fuel smell near the car, especially after refueling
  • difficulty refueling (nozzle clicks off)
  • slightly worse fuel economy
  • Check Engine Light on

What causes P240B?

  • failed evaporative emission system leak detection pump heater control pulling the signal low
  • missing supply voltage to the evaporative emission system leak detection pump heater control
  • signal wire shorted to ground (chafed insulation)
  • faulty vent valve or leak detection pump
  • faulty purge valve (canister purge solenoid)
  • saturated or damaged charcoal canister
  • cracked EVAP hoses or lines

How to diagnose P240B

  1. Connect an OBD2 scanner, confirm P240B is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
  2. Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
  3. Visually inspect the wiring harness and connectors related to the evaporative emission (EVAP) system for damage, corrosion, chafing or poor contact.
  4. Check for supply voltage at the evaporative emission system leak detection pump heater control connector first; then measure resistance from the signal wire to ground — near-zero ohms confirms a short to ground in the harness.
  5. Check the fuel cap first — it is the most common cause; inspect the seal and tighten until it clicks.
  6. Run an EVAP leak test (smoke test) to locate small leaks in hoses, canister and valves.
  7. Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P240B does not return.

How to fix P240B

Start with the cheapest and most common causes before replacing expensive parts:

  • Replace the fuel cap — $20–$60
  • Replace the purge or vent valve — $120–$350
  • Replace the charcoal canister — $250–$700

How much does it cost to fix P240B?

Repair cost depends on which component actually failed. Typical scenarios for P240B (parts and labor, USD, independent shop rates):

  • Replace the fuel cap: $20–$60
  • Replace the purge or vent valve: $120–$350
  • Replace the charcoal canister: $250–$700

Overall, fixing P240B usually costs between $20 and $700. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Can you drive with P240B?

Safe to drive. EVAP faults affect emissions, not drivability — you can keep using the car while planning the repair. Fuel vapour smell is a reason to fix it sooner: vapours are flammable and harmful.

Related OBD2 codes