Diagnostic trouble code (DTC) information

Condition 

Diagnostic trouble code (DTC) ECM-4020 is stored if the control module receives a signal from the fuel tank pressure sensor which corresponds to a pressure higher than 20 h Pa (0.29 psi) (high signal) or lower than -30 hPa (-0.435 psi) (low signal) and interprets it as a fault. If the signal is higher than 10 hPa (0.145 psi) directly after start-up with an engine coolant temperature (ECT) lower than 35°C (95°F), the control module interprets it as a fault (faulty signal) and diagnostic trouble code (DTC) ECM-4020 is stored.

Substitute Value 

leakage diagnostic is disabled

Possible Source 

Signal too high: 

• short-circuit to supply voltage in the signal cable
• open-circuit in the signal cable
• open-circuit in the ground lead.
• defective fuel tank pressure sensor

Signal too low: 

• short-circuit to ground in the signal cable
• short-circuit to ground in power cable
• defective fuel tank pressure sensor

Faulty signal: 

• contact resistance in terminals.
• defective fuel tank pressure sensor

Fault symptom[s] 

• none