dodge caliber engine light

Throwing codes dealer wants to replace the computer

po455 EVAPsystem large leak detected the dealer wants to replace the ESIM. why if its a leak

Most likely the dealer suspects the leak detection or reporting hardware (the EVAP system’s electronic leak detection module / ESIM) is faulty — not the physical EVAP plumbing — so replacing it can clear a false “large leak detected” code. Reasons they might replace the ESIM:

• Faulty leak detection sensor/circuit: The ESIM monitors pressure/flow and can report false large leaks if its sensor, pressure transducer, or internal electronics are out of spec.
• Intermittent electrical issues: Corroded connectors, wiring faults, or an ESIM that intermittently fails can trigger a persistent code even after EVAP plumbing checks.
• Diagnostic trouble code points to ESIM: Advanced scan data (live sensor readings, voltage, pressure traces) may show the module reporting impossible values (e.g., sudden large pressure drop without purge/vent events), indicating the module rather than a physical leak.
• Avoids unnecessary disassembly: Replacing the ESIM can be faster/cheaper than dismantling tanks, hoses, and charcoal canisters if diagnostics point to the control unit.

When to push back / confirm:

• Ask the dealer to show live diagnostic data and their test steps (smoke test, pressure test, wiring/connector checks) that led them to conclude the ESIM is at fault.
• Request they perform a smoke/pressure test on the EVAP system to confirm a physical leak is absent before replacing the module.
• If you want a second opinion, ask another trusted shop to run the same diagnostics.

If you want, tell me the vehicle make/year and the exact code(s) shown and I’ll explain typical failure modes and tests they should run.

Research:

dodge caliber mainstreet l4 2.0l is there any history of defects with this system, also explain the components, their locations and possible sensor locations for connector verification

Results:

History: The Caliber (2007–2012) and related Chrysler/Jeep models have a known history of EVAP-related trouble codes, often due to cracked/leaky EVAP hoses, failed purge solenoids/valves, leaking fuel filler necks, charcoal canister deterioration, and occasional faulty leak-detection modules/sensors. Large-leak DTCs can be caused by actual leaks or by failed EVAP control/electronic components giving incorrect pressure/readings.

EVAP system components (what they do)

• Fuel tank vent/rollover valve (VENT): Allows tank venting to the EVAP canister and closes on rollover.
• Charcoal canister (canister/purge canister): Stores fuel vapors.
• Purge solenoid/valve (Purge Valve): Controls flow of vapors from canister to intake manifold. Electrically actuated.
• EVAP pressure sensor / leak detection sensor: Monitors system pressure to detect leaks. On models with electronic leak detection (ELD/ESIM), this may be inside a module.
• Leak detection pump / ESIM (Evaporative System Integrity Module): Creates/monitors pressure changes to run system self-tests.
• Canister vent solenoid / vent valve: Opens to atmosphere when commanded during tests.
• Fuel filler neck and cap: Seals the system; cap leaks are common.
• Hoses and quick-connects: Connect tanks, canister, purge valve, vent valve, and filler neck.

Typical component locations on Dodge Caliber L4 2.0L (general layout)

• Charcoal canister: Behind right-side rear bumper area near the fuel tank or under rear quarter—mounted near the tank/canister bracket.
• Purge solenoid/valve: On or near the intake manifold or firewall in the engine bay; small cylindrical/plastic solenoid with two electrical pins and vacuum hose ports.
• Canister vent valve (vent solenoid): Near the charcoal canister or mounted low on the vehicle’s body near the tank/canister.
• EVAP pressure sensor / ESIM / leak-detection module: On many Chrysler small cars, the ESIM (or EVAP module) is mounted near the charcoal canister or integrated into the canister assembly or in the engine bay—locations vary by year/trim. It may be a small electronic module with one or more electrical connectors and vacuum lines.
• Fuel tank vent/rollover valve and hoses: On top of the fuel tank; accessible from under the car (requires lift) or by removing access panels.
• Fuel cap: Standard filler neck cap.

Common failure points for the Caliber

• Cracked/rotten rubber vacuum/EVAP hoses and fittings (heat/age).
• Faulty purge solenoid (stuck open/closed).
• Loose/missing/damaged fuel filler cap.
• Charcoal canister cracks or clogged canister.
• Faulty vent/rollover valve.
• Intermittent/faulty ESIM or pressure sensor (less common but reported).

Connector/sensor locations to verify (what to check)

• Purge solenoid connector: In engine bay — verify 2-pin connector for corrosion, bent pins, secure locking tab; check vacuum hose at top and bottom for cracks.
• Vent solenoid connector: Near canister — check similar 2-pin/3-pin connector and vacuum line.
• ESIM / EVAP module connector(s): Often a multi-pin electrical connector; inspect for corrosion, pushed-out pins, water intrusion, and secure clip. Wiggle test while monitoring live data can reveal intermittent faults.
• Pressure sensor connector (if separate): Small electrical plug on sensor — verify pins and harness for chafing.
• Ground connections and chassis grounds near fuel tank/canister: Corrosion here can create odd behavior.
• Fuel tank/filler neck hose connections: Inspect clamps, quick-connects, and the fuel cap seal.

Diagnostic verification steps you can request from the dealer (concise)

1. Smoke test to find any physical leaks (hose cracks, filler neck, canister).
2. EVAP system pressure/flow test using scan tool data: watch pressure sensor and ESIM live data while doing commanded tests.
3. Inspect/bench-test purge solenoid and vent solenoid (apply 12V; check resistance).
4. Inspect connectors and harness for corrosion or water intrusion; wiggle connectors while watching live data.
5. Swap or test ESIM if diagnostics show impossible values or if module self-test fails — but only after ruling out plumbing and wiring.

What to ask the dealer

• Show the smoke test result and live data traces (pressure vs time) that indicate module failure instead of a plumbing leak.
• Show connector inspection photos and resistance/voltage readings for purge/vent solenoids and pressure sensor.

If you want, I can give:

• Expected pinouts and connector photos for the Caliber 2.0L EVAP components (I’ll assume 2007–2012; tell me the model year if you want exact diagrams).