Code
U1308
CITROEN
U — Network/User
No communication with the engine management ECU fault: Missing engine control ECU / no signal
AI status
Completed
Completed
100%
Causes
- Blown fuse or disabled power/ignition feed to engine ECU
- Poor or missing ground connection(s)
- Damaged or disconnected wiring or connector to engine ECU
- CAN/LIN bus fault (short to ground/12V, open, high resistance)
- Faulty engine management ECU
- Faulty gateway/body control module or other network module
Symptoms
- Engine not starting or cranks but won't run
- No engine data displayed on dashboard (RPM, coolant temp, etc.)
- Multiple CAN/network-related faults present on scan tool
- Malfunction Indicator Lamp (MIL) or warning lights
- Intermittent engine operation or limp-home mode
- Loss of remote/central functions if gateway affected
What to check
- Read all module codes with a capable scan tool; note freeze frame and related U-codes
- Check battery voltage (should be 12.0–14.5 V) and battery connections
- Inspect/verify fuses and relays supplying engine ECU and gateway
- Visually inspect ECU connectors for corrosion, bent pins, or water ingress
- Check engine ECU power and ground pins for proper voltage and continuity
- Scan the CAN/LIN network for other modules that are not responding
Signal parameters
- Battery supply to ECU: ~11–14.5 V with key ON
- Ground continuity: near 0 Ω between ECU ground pin and chassis ground
- CAN bus idle voltages (recessive): CAN_H ≈ 2.5–3.0 V, CAN_L ≈ 2.0–2.5 V (both ~2.5 V typical)
- CAN bus dominant state: CAN_H ~3.5–4.0 V, CAN_L ~1.0–1.5 V during activity
- CAN bus differential voltage: typically 1.0–2.5 V when active
- Bus termination: 60 Ω between CAN_H and CAN_L (two 120 Ω parallel terminations)
Diagnostic algorithm
- Secure vehicle and record customer complaint and events leading to fault.
- Use a diagnostic tool to confirm U1308 and view related codes and freeze frame data.
- Check battery voltage and connections; ensure battery is healthy and fully charged.
- Verify fuses/relays for ECU power/ignition circuits; replace any blown fuses and re-test.
- Visually inspect engine ECU connector and harness for damage, corrosion or water ingress; repair as needed.
- Backprobe ECU power and ground pins to confirm proper supply voltage and good ground under key ON and cranking conditions.
- With key ON, measure CAN_H and CAN_L at the ECU connector; compare to expected idle and differential values.
- If bus voltages are incorrect, inspect for shorts to ground or battery, measure resistance to ground/12V on each bus line, and isolate sections of the network by disconnecting modules to find offending circuit.
- If bus is healthy but ECU does not respond, check for immobiliser/gateway inhibiting wake-up — verify authorization events and related codes.
- If wiring and power are good and other modules respond, consider ECU failure; confirm with substitution of a known-good ECU or bench test where possible.
- If ECU replacement is required, follow OEM procedures for programming, coding, and immobiliser pairing.
- Clear codes and verify repair by road test and re-scan for reoccurrence.
Likely causes
- Blown fuse or relay feeding the ECU
- Corroded/disconnected ECU connector or pin fault
- CAN bus short (most common on vehicles with multiple modules showing comms faults)
- Faulty engine ECU (less common than wiring issues)
- Immobiliser or gateway preventing ECU wake-up
Fault status
Status
No communication with engine management ECU — missing ECU or no signal present on vehicle network.
Repair difficulty: Hard
Diagnostic time: 2-6 hours
Similar codes
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Code
U1308
DS
U — Network/User
No communication with the engine management ECU fault: Missing engine control ECU / no signal
AI status
Completed
Completed
100%
Causes
- Blown fuse or disabled power/ignition feed to engine ECU
- Poor or missing ground connection(s)
- Damaged or disconnected wiring or connector to engine ECU
- CAN/LIN bus fault (short to ground/12V, open, high resistance)
- Faulty engine management ECU
- Faulty gateway/body control module or other network module
Symptoms
- Engine not starting or cranks but won't run
- No engine data displayed on dashboard (RPM, coolant temp, etc.)
- Multiple CAN/network-related faults present on scan tool
- Malfunction Indicator Lamp (MIL) or warning lights
- Intermittent engine operation or limp-home mode
- Loss of remote/central functions if gateway affected
What to check
- Read all module codes with a capable scan tool; note freeze frame and related U-codes
- Check battery voltage (should be 12.0–14.5 V) and battery connections
- Inspect/verify fuses and relays supplying engine ECU and gateway
- Visually inspect ECU connectors for corrosion, bent pins, or water ingress
- Check engine ECU power and ground pins for proper voltage and continuity
- Scan the CAN/LIN network for other modules that are not responding
Signal parameters
- Battery supply to ECU: ~11–14.5 V with key ON
- Ground continuity: near 0 Ω between ECU ground pin and chassis ground
- CAN bus idle voltages (recessive): CAN_H ≈ 2.5–3.0 V, CAN_L ≈ 2.0–2.5 V (both ~2.5 V typical)
- CAN bus dominant state: CAN_H ~3.5–4.0 V, CAN_L ~1.0–1.5 V during activity
- CAN bus differential voltage: typically 1.0–2.5 V when active
- Bus termination: 60 Ω between CAN_H and CAN_L (two 120 Ω parallel terminations)
Diagnostic algorithm
- Secure vehicle and record customer complaint and events leading to fault.
- Use a diagnostic tool to confirm U1308 and view related codes and freeze frame data.
- Check battery voltage and connections; ensure battery is healthy and fully charged.
- Verify fuses/relays for ECU power/ignition circuits; replace any blown fuses and re-test.
- Visually inspect engine ECU connector and harness for damage, corrosion or water ingress; repair as needed.
- Backprobe ECU power and ground pins to confirm proper supply voltage and good ground under key ON and cranking conditions.
- With key ON, measure CAN_H and CAN_L at the ECU connector; compare to expected idle and differential values.
- If bus voltages are incorrect, inspect for shorts to ground or battery, measure resistance to ground/12V on each bus line, and isolate sections of the network by disconnecting modules to find offending circuit.
- If bus is healthy but ECU does not respond, check for immobiliser/gateway inhibiting wake-up — verify authorization events and related codes.
- If wiring and power are good and other modules respond, consider ECU failure; confirm with substitution of a known-good ECU or bench test where possible.
- If ECU replacement is required, follow OEM procedures for programming, coding, and immobiliser pairing.
- Clear codes and verify repair by road test and re-scan for reoccurrence.
Likely causes
- Blown fuse or relay feeding the ECU
- Corroded/disconnected ECU connector or pin fault
- CAN bus short (most common on vehicles with multiple modules showing comms faults)
- Faulty engine ECU (less common than wiring issues)
- Immobiliser or gateway preventing ECU wake-up
Fault status
Status
No communication with engine management ECU — missing ECU or no signal present on vehicle network.
Repair difficulty: Hard
Diagnostic time: 2-6 hours
Similar codes
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Code
U1308
Other
U — Network/User
SCP (J1850) Invalid or Missing Data for Function Read Engine Torque
AI status
Completed
Completed
100%
Causes
- Blown fuse or disabled power/ignition feed to engine ECU
- Poor or missing ground connection(s)
- Damaged or disconnected wiring or connector to engine ECU
- CAN/LIN bus fault (short to ground/12V, open, high resistance)
- Faulty engine management ECU
- Faulty gateway/body control module or other network module
Symptoms
- Engine not starting or cranks but won't run
- No engine data displayed on dashboard (RPM, coolant temp, etc.)
- Multiple CAN/network-related faults present on scan tool
- Malfunction Indicator Lamp (MIL) or warning lights
- Intermittent engine operation or limp-home mode
- Loss of remote/central functions if gateway affected
What to check
- Read all module codes with a capable scan tool; note freeze frame and related U-codes
- Check battery voltage (should be 12.0–14.5 V) and battery connections
- Inspect/verify fuses and relays supplying engine ECU and gateway
- Visually inspect ECU connectors for corrosion, bent pins, or water ingress
- Check engine ECU power and ground pins for proper voltage and continuity
- Scan the CAN/LIN network for other modules that are not responding
Signal parameters
- Battery supply to ECU: ~11–14.5 V with key ON
- Ground continuity: near 0 Ω between ECU ground pin and chassis ground
- CAN bus idle voltages (recessive): CAN_H ≈ 2.5–3.0 V, CAN_L ≈ 2.0–2.5 V (both ~2.5 V typical)
- CAN bus dominant state: CAN_H ~3.5–4.0 V, CAN_L ~1.0–1.5 V during activity
- CAN bus differential voltage: typically 1.0–2.5 V when active
- Bus termination: 60 Ω between CAN_H and CAN_L (two 120 Ω parallel terminations)
Diagnostic algorithm
- Secure vehicle and record customer complaint and events leading to fault.
- Use a diagnostic tool to confirm U1308 and view related codes and freeze frame data.
- Check battery voltage and connections; ensure battery is healthy and fully charged.
- Verify fuses/relays for ECU power/ignition circuits; replace any blown fuses and re-test.
- Visually inspect engine ECU connector and harness for damage, corrosion or water ingress; repair as needed.
- Backprobe ECU power and ground pins to confirm proper supply voltage and good ground under key ON and cranking conditions.
- With key ON, measure CAN_H and CAN_L at the ECU connector; compare to expected idle and differential values.
- If bus voltages are incorrect, inspect for shorts to ground or battery, measure resistance to ground/12V on each bus line, and isolate sections of the network by disconnecting modules to find offending circuit.
- If bus is healthy but ECU does not respond, check for immobiliser/gateway inhibiting wake-up — verify authorization events and related codes.
- If wiring and power are good and other modules respond, consider ECU failure; confirm with substitution of a known-good ECU or bench test where possible.
- If ECU replacement is required, follow OEM procedures for programming, coding, and immobiliser pairing.
- Clear codes and verify repair by road test and re-scan for reoccurrence.
Likely causes
- Blown fuse or relay feeding the ECU
- Corroded/disconnected ECU connector or pin fault
- CAN bus short (most common on vehicles with multiple modules showing comms faults)
- Faulty engine ECU (less common than wiring issues)
- Immobiliser or gateway preventing ECU wake-up
Fault status
Status
No communication with engine management ECU — missing ECU or no signal present on vehicle network.
Repair difficulty: Hard
Diagnostic time: 2-6 hours
Similar codes
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Code
U1308
PEUGEOT
U — Network/User
No communication with the engine management ECU fault: Missing engine control ECU / no signal
AI status
Completed
Completed
100%
Causes
- Blown fuse or disabled power/ignition feed to engine ECU
- Poor or missing ground connection(s)
- Damaged or disconnected wiring or connector to engine ECU
- CAN/LIN bus fault (short to ground/12V, open, high resistance)
- Faulty engine management ECU
- Faulty gateway/body control module or other network module
Symptoms
- Engine not starting or cranks but won't run
- No engine data displayed on dashboard (RPM, coolant temp, etc.)
- Multiple CAN/network-related faults present on scan tool
- Malfunction Indicator Lamp (MIL) or warning lights
- Intermittent engine operation or limp-home mode
- Loss of remote/central functions if gateway affected
What to check
- Read all module codes with a capable scan tool; note freeze frame and related U-codes
- Check battery voltage (should be 12.0–14.5 V) and battery connections
- Inspect/verify fuses and relays supplying engine ECU and gateway
- Visually inspect ECU connectors for corrosion, bent pins, or water ingress
- Check engine ECU power and ground pins for proper voltage and continuity
- Scan the CAN/LIN network for other modules that are not responding
Signal parameters
- Battery supply to ECU: ~11–14.5 V with key ON
- Ground continuity: near 0 Ω between ECU ground pin and chassis ground
- CAN bus idle voltages (recessive): CAN_H ≈ 2.5–3.0 V, CAN_L ≈ 2.0–2.5 V (both ~2.5 V typical)
- CAN bus dominant state: CAN_H ~3.5–4.0 V, CAN_L ~1.0–1.5 V during activity
- CAN bus differential voltage: typically 1.0–2.5 V when active
- Bus termination: 60 Ω between CAN_H and CAN_L (two 120 Ω parallel terminations)
Diagnostic algorithm
- Secure vehicle and record customer complaint and events leading to fault.
- Use a diagnostic tool to confirm U1308 and view related codes and freeze frame data.
- Check battery voltage and connections; ensure battery is healthy and fully charged.
- Verify fuses/relays for ECU power/ignition circuits; replace any blown fuses and re-test.
- Visually inspect engine ECU connector and harness for damage, corrosion or water ingress; repair as needed.
- Backprobe ECU power and ground pins to confirm proper supply voltage and good ground under key ON and cranking conditions.
- With key ON, measure CAN_H and CAN_L at the ECU connector; compare to expected idle and differential values.
- If bus voltages are incorrect, inspect for shorts to ground or battery, measure resistance to ground/12V on each bus line, and isolate sections of the network by disconnecting modules to find offending circuit.
- If bus is healthy but ECU does not respond, check for immobiliser/gateway inhibiting wake-up — verify authorization events and related codes.
- If wiring and power are good and other modules respond, consider ECU failure; confirm with substitution of a known-good ECU or bench test where possible.
- If ECU replacement is required, follow OEM procedures for programming, coding, and immobiliser pairing.
- Clear codes and verify repair by road test and re-scan for reoccurrence.
Likely causes
- Blown fuse or relay feeding the ECU
- Corroded/disconnected ECU connector or pin fault
- CAN bus short (most common on vehicles with multiple modules showing comms faults)
- Faulty engine ECU (less common than wiring issues)
- Immobiliser or gateway preventing ECU wake-up
Fault status
Status
No communication with engine management ECU — missing ECU or no signal present on vehicle network.
Repair difficulty: Hard
Diagnostic time: 2-6 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
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Send to email