Code
U0699
Generic
U — Network/User
Lost Communication with Coolant Pump “F”
Views:
UK: 12
EN: 22
RU: 18
AI status
Completed
Completed
100%
Causes
- Failed coolant pump control or monitoring module
- Open or shorted wiring between the pump module and network or power/ground
- Corroded or loose connector at the pump module or harness
- Blown fuse or failed relay supplying the pump/module
- Fault on the vehicle communication bus (CAN/LIN) such as missing termination or damaged wiring
- Software or module internal fault (module hung or corrupted)
Symptoms
- Stored U0699 (and possibly other U-codes) in one or more modules
- Coolant pump F may not run or run intermittently
- Poor coolant circulation, engine running hot or temperature regulation issues
- Illumination of warning lamp(s) related to emission or powertrain (depends on vehicle)
- Reduced cooling performance or vehicle limp-home mode in some systems
- No response from coolant pump F when commanded by a scan tool
What to check
- Scan all modules; record U0699 and any other related U- or P-codes and freeze frame data
- Check battery voltage and charging system; ensure 12V supply is stable
- Inspect connectors and wiring at coolant pump F for corrosion, damage, or loose pins
- Verify fuse(s) and relay(s) feeding the pump/module
- Attempt communication with the pump module using a capable scan tool
- Check CAN/LIN bus health: measure bus voltages, verify termination resistance, and look for shorts to power/ground
Signal parameters
- Module supply voltage: nominal 11–14 V when key on/run
- Ground: low resistance to chassis (typically
- CAN bus idle voltages: CANH ≈ 2.5 V, CANL ≈ 2.5 V (recessive); dominant CANH ≈ 3.5 V, CANL ≈ 1.5 V
- CAN bus differential voltage when active: typically ~2.0 V
- Expected termination resistance: about 60 Ω total (two 120 Ω resistors in parallel on most vehicles)
- Message frequency/IDs: coolant pump status/control frames vary by manufacturer (verify ID and expected rate with service data)
Diagnostic algorithm
- Read and record all stored DTCs and freeze frame data from all modules. Note occurrence conditions.
- Clear codes. Attempt to communicate with coolant pump F using scan tool; see if code returns.
- Verify battery and charging system voltage. Low voltage can cause modules to drop off network.
- Visually inspect connectors, pins and harness to coolant pump F. Repair any corrosion or damage.
- With key on and engine off, check for proper power and ground at the pump module connector (measure 12V and ground continuity).
- Inspect/replace any related fuses or relays. Re-test communication after replacement.
- Check CAN/LIN bus continuity and resistance. Measure CANH/CANL voltages at several nodes; compare to specification.
- Perform wiggle test and watch for intermittent communication while moving harness/connector.
- If wiring, power and bus look good but no communication, attempt reprogramming or re-flash per manufacturer instructions if available.
- If module still does not communicate and all vehicle-side checks are good, replace coolant pump module and verify repair.
- After repairs, clear codes and perform road/test and re-scan to confirm U0699 does not return.
Likely causes
- Damaged or disconnected connector at the coolant pump module
- Faulty power or ground to the pump module (blown fuse, poor ground)
- CAN/LIN wiring open, shorted, or high resistance between module and network
- Corroded pins causing intermittent communication
- Module failure (most likely if wiring and power check good)
Fault status
Status
Lost Communication with Coolant Pump "F" — the coolant pump module is not responding on the vehicle communication network.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Workshop Manuals
Available brands with manuals
2
AUDI 11
6-speed manual gearbox 0B1, front-wheel drive — Workshop Manual (Edition 05.2014)
Workshop Manual199,00 UAH
Audi A3 (1997) – 1.6L 4-cylinder (2‑valve) Engine Mechanical Components Service Manual (AEH, AKL, APF) – Edition 07.2002
Workshop Manual199,00 UAH
AUDI A3 (2004) Workshop Manual — 2.0L FSI Turbo (4‑cyl, 4‑valve) Engine, Mechanics — Edition 03.2017
Workshop Manual199,00 UAH
Audi A3 2004 — Electrical System (Workshop Manual, Edition 02.2018)
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet – 4.2 l V8 (5‑valve, timing chains) – Workshop Manual (Mechanics) – Edition 04.2007
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet — Auxiliary Heater Workshop Manual (Edition 08.2004)
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet (1.8T 4‑cyl turbo) — Motronic Injection & Ignition System Service Manual (Edition 01.2015)
Workshop Manual199,00 UAH
Audi A8 (2003) — Electrical System Workshop Manual (Edition 08.2014)
Workshop Manual199,00 UAH
Audi Q4 e-tron (Type F4) - Self-study Programme SSP 685
Workshop Manual199,00 UAH
Audi Q8 (2018) — Electrical System Workshop Manual (Edition 05.2019)
Workshop Manual199,00 UAH
Audi Servicing Manual — 7‑Speed Dual Clutch Transmission 0CJ / 0CL / 0CK / 0DN / 0DP / 0HL (Edition 05.2018)
Workshop Manual199,00 UAH
LAND ROVER 3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop Manual199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop Manual199,00 UAH
Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop Manual199,00 UAH
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