P20E9 — Reductant pressure — pressure too high

P20E9 concerns reductant pressure. The monitored pressure is reported as exceeding the accepted operating limit. The reported variable is reductant pressure. The definition gives no universal pressure limit and does not specify which component caused the condition.

Affected system: Reductant dosing and SCR aftertreatment

Symptoms

• Warning light may illuminate
• Related system function may be impaired
• Vehicle-specific symptoms vary

Possible causes

• Implausible sensor or switch signal, poor ground, connector corrosion, or wiring damage
• Related wiring, connector, power or ground fault
• Vehicle-specific mechanical or control issue

What to check

• Record stored and pending codes and freeze-frame data
• Compare the named sensor or switch signal with actual operating conditions; inspect the connector, reference supply, ground and harness.
• Confirm measured values against the vehicle service information
• Retest under the conditions that set the code
• Compare the named sensor or switch signal with actual operating conditions; inspect the connector, reference supply, ground and harness.
• Repair the verified cause and confirm the code does not return

Also written as: P20E9-00, P20E900 (some scan tools add the fault-type byte, e.g. -00).