Danger | Risk of death. Death may occur if body parts are drawn into rotating vehicle parts. | Do not insert your hand into rotating parts. Wear closed and snug-fitting work clothes. Secure area of rotating vehicle components against unauthorized access. | |
Danger | Risk of death when working on component parts and systems with U >= 30 V alternating voltage (AC) or U >= 60 V direct voltage (DC) | Do not touch damaged or defective live component parts and lines or non-insulated electrical connections and lines. | |
Danger | Risk of explosion caused by fuel igniting, risk of poisoning caused by inhaling and swallowing fuel as well as risk of injury to eyes and skin caused by contactwith fuel. | No fires, sparks, open flames or smoking. Pour fuels into suitable and appropriately marked containers only. | |
ECM fuel injection and ignition system, diagnosis, basic knowledge | |||
Troubleshooting | |||
Complaint | Possible cause | Notes | Remedy |
Engine slow to start and accelerate | Injection valves actuation and injection duration | 3/11 | |
Hot film MAF sensor (B2/5) | 2/11 | See HHT test program | |
Coolant temperature sensor (B11/4) | 1/11 | ||
Ignition voltage too low | – | ||
Unmetered air | – | Eliminate unmetered air | |
Low fuel grade | – | Check fuel for presence of water and diesel | |
Intake valves carbonized | – | Check intake tract for oil ingress, eliminate if necessary | |
Engine fails to start | Power supply missing | – | |
Safety time between ignition ON and engine start exceeded (>30 min) | - | Ignition: OFF and restart engine | |
Malfunction in drive authorization system (DAS) | Drive authorization 1/2 | ||
Fuel pump (FP) | – | ||
No compression pressure as oil pressure too high | – | Check compression pressure and/or oil pressure | |
Ignition voltage too low | – | ||
Engine has rough idling | Injection valves actuation and injection duration | 3/11 | |
Unmetered air | – | Eliminate unmetered air | |
Poor engine output | Catalytic converter has too low flow rate | – | |
O2Lambda sensor upstream of catalytic converter | 8/11 | ||
Coolant temperature sensor (B11/4) | 4/11 | ||
Hot film MAF sensor (B2/5) | 2/11 | See HHT test program | |
3/11 | |||
4/11 | |||
6/9 | |||
Engine runs irregularly (shakes) | Injection valves actuation and injection duration | 3/11 | |
Injection valves leaky, spray pattern | – | ||
O2Lambda sensor upstream of catalytic converter | 8/11 | ||
Ignition voltage too low | – | ||
Compression pressure of one or more cylinders too low | – | Check compression pressure | |
Unmetered air | – | Eliminate unmetered air | |
Engine runs irregularly (misfire) | Ignition voltage too low | – | |
Hot film MAF sensor (B2/5) | 2/11 | See HHT test program | |
Engine surges after cold start | Unmetered air | – | Eliminate unmetered air |
Transition fault in warm-up | Coolant temperature sensor (B11/4) | 4/11 | |
Hot film MAF sensor (B2/5) | 2/11 | See HHT test program | |
Unmetered air | – | Eliminate unmetered air | |
Transition fault in warm-up and/or poor fuel economy | O2Lambda sensor upstream of catalytic converter | 8/11 | |
Left purge control valve | 4/11 | ||
Engine jerks | Hot film MAF sensor (B2/5) | 2/11 | See HHT test program |
Ignition voltage too low | – | ||
O2Lambda sensor upstream of catalytic converter | 8/11 | ||
Referenced documents
- ad0753p2000a ECM fuel injection and ignition system, diagnosis, basic knowledge
- ad0753p2000a
- as0000z000401a Risk of death. Death may occur if body parts are drawn into rotating vehicle parts.
- as0000z003501a Risk of death when working on component parts and systems with U >= 30 V alternating voltage (AC) or U >= 60 V direct voltage (DC)
- as4700z000101a Risk of explosion caused by fuel igniting, risk of poisoning caused by inhaling and swallowing fuel as well as risk of injury to eyes and skin caused by contactwith fuel.