P240B — Evaporative Emission System Leak Detection Pump Heater Control #

Note: The code description may vary depending on the vehicle manufacturer.

• P240B: EVAP System Leak Detection Pump Heater Control Circuit (Ford, GM, Toyota)
• P240B: EVAP Leak Detection Pump Heater Control Circuit/Open (BMW)
• P240B: Leak Detection Pump Heater Control Circuit Low (Volkswagen/Audi)

Code Summary for P240B #

The P240B diagnostic trouble code (DTC) indicates an issue with the Evaporative Emission (EVAP) System Leak Detection Pump Heater Control circuit. In simple terms, the vehicle’s engine control module (ECM) or powertrain control module (PCM) has detected a fault related to the heater that helps the leak detection pump function correctly within the EVAP system. The EVAP system is responsible for preventing fuel vapors from escaping into the atmosphere by storing them in a charcoal canister until they can be burned by the engine. The leak detection pump is a component that pressurizes the system to check for leaks, and its heater ensures the pump operates effectively in varying temperatures. When the heater circuit malfunctions, the system may not accurately detect vapor leaks, triggering the P240B code. This is an emissions-related issue, and while it seldom causes immediate drivability problems, it does require timely attention to prevent further complications.

Common Symptoms for Code P240B #

Interestingly, a vehicle with a P240B code often runs seemingly fine, making the issue easy to overlook. However, certain symptoms can emerge, especially over time or with significant faults. Key symptoms include:

• Illuminated “Check Engine” light (MIL) — the most common and sometimes only sign.
• Failed emissions test — due to inability to verify EVAP system integrity.
• Fuel odor — in rare cases, if other EVAP components are affected.
• Sporadic rough idle or hesitation — very uncommon, but possible if EVAP leaks are substantial.
• Increased emissions — not typically noticeable by the driver but measurable on inspection.

Most Probable Causes for Code P240B #

The P240B code is usually linked to electrical or component faults within the leak detection pump heater circuit. Causes vary in frequency, but most stem from one of these sources:

1. Faulty leak detection pump heater — the heater element itself fails (most common).
2. Wiring issues — damaged, shorted, or corroded wires/connectors in the heater circuit.
3. Defective leak detection pump — the entire pump assembly malfunctions, including the heater.
4. Blown fuse or relay — protects the circuit but may fail due to age or electrical surges.
5. Faulty PCM/ECM — rare, but possible if the control module cannot drive the heater circuit.

Step-By-Step Diagnostics for Code P240B #

Diagnosing the P240B code requires a methodical approach to avoid replacing parts unnecessarily. Here’s a proven step-by-step process:

1. Scan and record all trouble codes — check for related EVAP or electrical codes.
2. Inspect the leak detection pump and heater wiring — look for damaged, melted, or corroded wires/connectors.
3. Check the fuse and relay — ensure the circuit’s fuse/relay is intact and functioning.
4. Test the heater element — using a multimeter, verify resistance is within OEM specifications (refer to repair manual).
5. Command the heater on via scan tool — see if the PCM can activate the circuit and watch for voltage at the pump.
6. Inspect the leak detection pump assembly — if accessible, check for physical damage or contamination.
7. Test PCM/ECM output — if all else checks out, ensure the control module is sending the correct signals.
8. Clear codes and retest — after repairs, clear the code and perform an EVAP system test drive cycle.

Possible Repairs for Code P240B #

Once the root cause is identified, repairs for P240B are fairly straightforward, though accessibility can vary by vehicle. Common solutions include:

• Repair or replace damaged heater wiring or connectors.
• Replace the leak detection pump heater or the entire pump assembly if integrated.
• Replace a blown fuse or malfunctioning relay associated with the heater circuit.
• Repair or replace PCM/ECM — only if verified as faulty after all other steps.
• Clear codes and perform a drive cycle to confirm the repair.

Is It Safe to Drive With Code P240B? #

Limited — but not urgent, unless emissions testing is due. Your vehicle will usually operate normally with code P240B set, as it does not impact engine performance or safety directly. However, the EVAP system’s inability to detect leaks may allow fuel vapors to escape, increasing emissions and possibly triggering further diagnostic codes. If your area requires regular emissions testing, this code will likely cause a failure, so timely repair is advised.

Vehicles Most Commonly Affected by P240B #

While P240B can appear on various makes, certain manufacturers and models are more frequently associated with this code due to their leak detection pump design:

• Volkswagen/Audi (especially Jetta, Passat, A3/A4, Tiguan)
• BMW (notably 3 Series, X3/X5)
• Toyota/Lexus (Camry, Corolla, RAV4, ES series)
• Ford (Focus, Escape, Fusion)
• General Motors (Chevrolet, GMC, Buick) — select models with advanced EVAP systems

Frequent Mistakes and Best Practices for Code P240B #

Many technicians and DIYers encounter pitfalls when addressing P240B, often leading to unnecessary expenses or repeat repairs. Here’s what to avoid and what to do:

• Replacing the leak detection pump without testing the heater circuit — always check wiring/fuses first.
• Ignoring related codes — secondary EVAP or electrical codes may pinpoint the real issue.
• Assuming PCM/ECM failure prematurely — this is rare; exhaust all circuit/component tests first.
• Skipping a post-repair drive cycle — always clear codes and confirm the repair under real conditions.
• Referencing OEM wiring diagrams — essential for proper testing and repair.

P240B Fast FAQ #

Need quick answers? Here are the most common questions about the P240B code:

• Q: Does P240B mean my car will fail a smog or emissions test?
  A: Yes, in most regions, an active P240B code will trigger a check engine light and cause automatic failure.
• Q: Can I just clear the code and pass inspection?
  A: No. Most inspection systems check if the code reappears or if readiness monitors have reset. The underlying issue must be repaired.
• Q: Is the leak detection pump heater expensive to replace?
  A: Costs vary, but for many vehicles, the heater is integrated with the pump, making replacement moderately expensive. Labor costs can add up if the pump is hard to access.