Roewe Plug-in Hybrid On-Board Charger (OBC) Fault Diagnosis Guide

Fault Background

The on-board charger (OBC) of the Roewe plug-in hybrid (manual 846) connects to the high-voltage distribution system via high-voltage interfaces HV001/HV002. On the low-voltage side, it interacts with the vehicle through BY222/BY223. During power-up, it triggers communication via the wake-up signal and confirms the start of charging. The code table covers the complete chain from grid input to high-voltage output, with quantified thresholds: AC voltage <70V / >280V for 100ms, PFC output bus >465V / <300V, high-voltage battery pack voltage >455V for 1s / <190V for 5s, primary temperature >127℃ / secondary >122℃ for 5s, ambient temperature <-35℃ / >115℃ / >95℃, charge port positive terminal >110℃, CP control signal at 9V high level, load PWM <8% or >90% for 200ms, output power >20% of maximum power. Fault actions are divided into two levels: "reset 5 times still present → shutdown/limit" and "immediately shut down the charger". This article organizes a diagnostic quick-reference guide in chain order.

AC Input and PFC Family

High-Voltage Output Family

• P1FA6 High-voltage battery pack output voltage >455V for 1s;
• P1FA7 High-voltage battery pack output voltage <190V for 5s;
• P1FA8 High-voltage output related (same family).

Diagnostic path: Clear codes and retest → Check OBC and vehicle wiring harness connectors (HV001/HV002, etc.) for looseness/poor contact → Ignition OFF, wait more than 5 minutes, operate the manual service disconnect switch to cut off high-voltage battery power, disconnect the 12V battery negative terminal → Measure between terminals of the high-voltage battery connector and between terminals and ground to confirm no high voltage → Disconnect HV002 and measure the circuit → If still reported, inspect/replace the on-board charger.

Temperature Family (Primary / Secondary / Ambient / Charge Port)

Handling: Clear codes and retest → Check charge port/wiring harness connectors → Check coolant level and contamination → If cooling system is normal but still reported → Inspect/replace OBC.

Charging Control Family

• P1FC0 Charging cable connection control signal at 9V high level sustained (CP line abnormal—normal CP switches between 6V/9V; constant 9V indicates charging station/cable side issue);
• P1FC1 Charging cable connection control load circuit PWM <8% or >90% for 200ms;
• P1FC2 Output power >20% of maximum power; when actual output power is less than allowed output power, restart every 10s;
• P1FC3/P1FC4/P1FC5 Charging cable/charge port connection family—Check slow charge port connector BY227 and on-board charger BY223 terminal circuit (threshold like <5Ω); Reset 5 times still present → Limit output power and input current.

Communication and Internal Family

• P1FA9/P1FAA Communication fault between master and slave control units for 10s—Check OBC internal communication wiring and connectors;
• P1FAB Wake-up signal family—Check wake-up circuit (conduction threshold <5Ω);
• U2001 OBC controller detects EEPROM read/write error → Charging accuracy deteriorates; U2002 RAM read/write error → Shut down on-board charger; U2005 Memory write calculation checksum error → Shut down on-board charger;
• U1562/U1563 Supply voltage family: Charging voltage continuously below 6V (U1563), etc.—Check battery voltage, fuses, and BY222-11 ↔ BY223-11 circuit;
• U0074/U1111 CAN communication class—Check high-speed CAN network integrity.

Safety Warnings

• This article is for technical reference. OBC inspection involves high voltage (input threshold 190~455V) and AC grid side; must be performed by qualified technicians (electrician certificate + company training authorization) according to OEM specifications.
• Before high-voltage circuit testing: Ignition OFF, wait more than 5 minutes, operate the manual service disconnect switch to cut off high-voltage battery power, disconnect the 12V battery negative terminal, and confirm no high voltage on terminals.
• AC side measurement (70V/280V thresholds) requires live-line protection; charge port temperature code (>110℃) indicates risk of poor contact at charge port; disconnect charging gun before inspection.
• After replacing OBC, perform module self-learning and adjustment, programming and coding.

Maintenance Insights

The Roewe OBC code table divides the charging chain into five sections with individual thresholds. The most practical is the "voltage three-window": AC input 70~280V, PFC bus 300~465V, high-voltage output 190~455V—when a code is reported, first see which section it falls into: P1FA0/1 is grid side (check supply voltage and charging station), P1FA3/4 is PFC internal (directly points to OBC), P1FA6/7 is high-voltage battery pack side (first check battery pack and HV002 harness). The temperature family is "five-point temperature measurement + three-level action": primary 127℃/secondary 122℃ is power stage overheating, ambient 95℃ (5s) immediate shutdown, 115℃ (1s) reset 5 times before shutdown—note the difference in action levels. Behavioral details worth remembering: P1FC2 output power limited "restart every 10s", similar to DCDC's 2s×5 restarts, is controller self-rescue; don't mistake periodic fluctuation as a fault when measuring; P1FC0 "CP constant 9V" indicates the charging station/cable hasn't pulled CP down to 6V charging state—try another station/cable before suspecting the vehicle. Finally, the internal family U2001/U2002/U2005 (EEPROM/RAM/checksum): EEPROM error only "charging accuracy deteriorates", RAM/checksum error directly shuts down—repair by level, not necessarily replace parts.

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【This article is for reference only】