P2055 indicates a high voltage condition in the reductant (DEF) injection valve circuit for Bank 1 Unit 2. This code is set when the powertrain control module (PCM) detects a voltage above the expected range on the valve control circuit, often due to a short to power or an internal fault in the valve.
The valve itself may have an internal short to power or high resistance, causing the circuit voltage to be high. This is the most common failure.
A chafed wire or damaged connector can create a direct short to a 12V source, raising the circuit voltage above the expected level.
Poor connection or corrosion at the valve connector can cause intermittent high voltage readings.
A failed PCM is a rare cause but can produce a false high voltage reading. This should only be considered after all other possibilities are eliminated.
You may be able to drive, but the vehicle will likely enter a reduced power mode to protect the emissions system. Continued driving could cause further damage or clog the diesel particulate filter (DPF).
No. While a faulty injector is the most common cause, wiring issues such as a short to power or a damaged connector are also frequent. The PCM itself is rarely the cause.
Almost never. Many drivers are told the PCM is faulty, but for P2055 the problem is almost always the valve or its wiring. Only replace the PCM after thorough diagnosis confirms it.
Bank 1 refers to the side of the engine containing cylinder #1. Unit 2 indicates the second DEF injector on that bank, as some systems use multiple injectors for precise dosing.