Code
P1622
BMW
P — Powertrain
MAP Cooling Control Circuit Electrical
Views:
UK: 27
EN: 53
RU: 36
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring in MAP cooling control circuit
- Corroded, loose or damaged connector(s)
- Failed MAP cooling control solenoid/valve/actuator
- Blown fuse or faulty relay supplying the circuit
- Poor ground or high resistance ground connection
- Water ingress or contamination of connector
Symptoms
- Check Engine Light (MIL) illuminated
- Reduced engine performance or limp mode (possible)
- Unusual MAP or intake charge temperatures reported in live data
- Intermittent operation of MAP cooling system components
- Possible related turbo or charge-air overheating symptoms
What to check
- Read and record freeze frame and live data (MAP pressure, MAP temp, related duty cycle)
- Check for stored additional manufacturer codes that give context
- Visually inspect wiring, harness and connectors for damage or corrosion
- Check fuses and relays supplying the MAP cooling circuit
- Measure supply voltage and ground at the actuator connector with key on/engine off
- Measure coil/actuator resistance with connector disconnected
Signal parameters
- Expected supply voltage at actuator: ~12 V (battery voltage) with ignition ON (verify per model)
- Expected ground: low resistance to chassis (near 0 ohms)
- Typical solenoid coil resistance: 10–100 ohms (model dependent) — open if >>1000 ohms, short if
- Control signal: either switched 12 V or PWM/duty cycle 0–100% from ECU (verify with scope/scan tool)
- MAP and MAP-temperature sensor values: should be within normal ranges for engine state
Diagnostic algorithm
- Retrieve DTCs and freeze frame data. Note conditions when fault set.
- Inspect visible wiring, connectors and harness routing for damage, heat or corrosion near actuator and ECU.
- Verify related fuses and relays. Replace if faulty and retest.
- With ignition ON, backprobe actuator connector: verify presence of supply voltage and good ground. If missing, trace supply/ground to fuse/relay/ground point.
- With connector disconnected, measure actuator coil resistance. Compare to vehicle specification; replace actuator if out of range.
- If supply and coil resistance OK, reconnect and use a scan tool or scope to monitor control signal while commanding the actuator ON/OFF. Verify ECU is commanding and that command produces expected voltage/duty.
- Perform a wiggle/inspection test on harness while monitoring for intermittent changes in live data or DTC status.
- If wiring and actuator test good but no proper command or abnormal signals, suspect ECU driver fault — confirm by checking other outputs or consulting manufacturer guidance before replacing ECU.
- After repairs, erase codes and perform test drive to confirm DTC does not return and system operates correctly.
Likely causes
- Connector corrosion/water intrusion at the solenoid or harness
- Broken/chafed wire between ECU and MAP cooling actuator
- Failed MAP cooling solenoid (open coil or shorted coil)
- Faulty fuse or relay in related power feed
- Poor ground at engine/chassis grounding point
Fault status
Status
Electrical fault detected in MAP cooling control circuit — check wiring, connector, fuse/relay and actuator
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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