U2207 — CAN-Bus No Communication with UHP(Mobile Phone Portal)

Causes

• UHP (mobile phone portal) powered off, faulty, or in a bus‑off state
• Open, short or intermittent wiring in the CAN bus to the UHP (broken conductor, chafing, connector corrosion)
• Poor or missing ground or supply voltage to the UHP
• Faulty CAN termination resistor(s) or incorrect bus impedance
• Connector pin corrosion, bent pins, or poor mating at UHP or gateway modules
• Other module(s) on same CAN segment causing bus error (short to battery/ground)

Symptoms

• Hands‑free/mobile phone portal unavailable or not detected by infotainment
• Phone pairing fails or is intermittent
• No audio/phone functions from UHP module
• DTC U2207 stored; possibly other network communication DTCs present
• Infotainment display may show ‘no device’ or similar message
• Intermittent CAN bus errors, features on same bus may be affected

What to check

• Read all stored and pending U‑codes and related network DTCs with a capable scan tool
• Confirm whether UHP responds to diagnostic communication (invoke module presence/list)
• Check for other modules on same CAN segment reporting errors
• Visually inspect UHP connector and harness for corrosion, bent pins, water damage, or mechanical strain
• With ignition ON, measure supply voltage and ground at UHP connector pins (compare to vehicle nominal battery voltage and chassis ground)
• Measure CAN bus idle voltages: CAN H and CAN L at/near UHP and at gateway/module (see signal params)

Signal parameters

• Typical CAN idle voltages: CAN H ≈ 2.5 V, CAN L ≈ 2.5 V (nodes vary ±0.5 V); dominant state reduces CAN H and raises CAN L differential ≈1.5 V+
• Expected differential when dominant: CAN H ~3.5–4.0 V, CAN L ~1.0–1.5 V (vehicle dependent)
• Bus end‑to‑end termination: two 120 Ω resistors in parallel -> approx. 60 Ω between CAN H and CAN L (measure with power off)
• Common bus speeds: HS CAN often 500 kb/s; some networks 250 kb/s or 125 kb/s — verify vehicle documentation
• Expected: periodic UHP CAN messages present on that segment when the module is operational (message IDs and frequency per OEM specification)

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