Evaporative Emissions System: Testing and Inspection

Evaporative Emissions - VIN Range: G45704->G99999

Overview

2006my changes
There are changes to the engine management system (EMS) for 2006 my, the most obvious of which will be the change to 7-digit diagnostic trouble codes (DTCs) from the familiar 5-digit, plus the addition of secondary air injection and changes to Federal evaporative emissions (Europe is unchanged) and all market exhaust gas recirculation to comply with stage four emissions requirements.

The hardware changes to the Federal evaporative emissions system are the deletion of the canister close valve and the fuel tank pressure sensor, which have been replaced with a combined unit incorporating a DMTL (diagnostic monitoring of tank leakage) pump and a COV (change-over valve) into one module.

The software changes will have more effect on the technician, as there is no longer the need to carry out extensive drive cycles to confirm the success of a repair.

DMTL conditions
The DMTL test is performed after the engine has stopped following a 10 minute run, providing that the vehicle fuel tank is between 15 and 85 percentfull and that the ambient temperature is above 0 degrees C (32 degrees F) and less than 40 degrees C (104 degrees F).

The DMTL pump is driven to pressurize the fuel tank and the current is measured with the change-over valve in different states.

A comparison of the current draw in each state indicates the degree of any leak, and the ECM then sets the appropriate DTC.

Inspection and verification
1. Visually inspect for obvious signs of mechanical or electrical damage.
2. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

Mechanical Electrical
Fuel filler cap and seal Fuses
Fuel filler neck Connectors
DMTL fresh air filter (restriction, etc) Harness(es)
Fuel tank (leaks, damage, etc) Purge valve
Fuel lines and joints, etc DMTL pump
Carbon canister
Purge valve
DMTL pump module

3. If the cause is not visually evident use the Jaguar approved diagnostic system or a scan tool to retrieve the fault codes before proceeding to the DTC Index.
4. Where K-Line or Vacutec equipment is available, it should be used as an aid to diagnosis.