Symptom selector
Type a symptom, code, or system (e.g., “no crank”, “P0420”, “DPF”, “charging”). Use the tags for quick filtering.
Tip: you can stack tags (e.g., engine + emissions) and still search within the results.
Results
No crank
Key turned but starter doesn’t engage.
Crank no-start
Starter turns the engine but it won’t fire.
Hot/cold no-start
Starts only when hot or only when cold.
Stalling / cutting out
Engine dies intermittently.
Rough idle / misfire
Unstable idle, shaking, or misfire.
P0300 random misfire
Multiple-cylinder misfire pattern.
Single-cylinder misfire (P0301–P0308)
Targeted checks for one cylinder.
P0171 / P0172 fuel trim
Lean/rich patterns by trims.
P0101 MAF performance
Airflow plausibility checks.
P0420 catalyst efficiency
Cat/O2/exhaust leak logic.
DPF / EGR limp mode
Diesel limp patterns and checks.
DPF regen decision
When to regen vs stop.
P0401 / P0402 EGR flow
EGR plausibility decision flow.
Petrol no power / limp
Common petrol limp patterns.
Boost loss / underboost
Turbo boost control checks.
Overboost
Overboost root-cause logic.
P0011 / P0014 VVT performance
Oil/VVT solenoid/cam timing checks.
P013x O2 / lambda circuit & heater
Sensor circuit vs fueling sanity checks.
P2101/P2135 throttle/APP faults
ETC limp, wiring and relearn flow.
P0087 low fuel rail pressure
Supply vs high-pressure side logic.
U0121 lost communication with ABS
ABS module power/ground/CAN checks.
Overheating
Cooling system decision flow.
Coolant loss / pressure test
Find leaks and rule out HG.
P0128 thermostat rationality
Warm-up and sensor plausibility.
Battery / charging
Charging system flow.
U0100/U0121 comms patterns
Network plausibility logic.
U0100 lost comms with ECM/PCM
Power/ground/CAN physical checks.
ABS / traction warnings
Wheel speed, tone rings, power/ground.
Brake judder vs ABS
Differentiate judder from ABS intervention.
Brake pedal vibration
Pedal feel diagnosis flow.
AC not cold
Basic A/C checks and branching.
P2002 DPF efficiency
DPF pressure and regen prerequisite checks.
P2563 turbo actuator position
Actuator movement and wiring checks.
P2187 lean at idle
Idle-only lean logic: air leaks, purge, MAF.
P2196 O2 stuck rich
Sensor bias vs true rich condition checks.
U0140 BCM communication
Power, ground, and CAN checks for BCM.
U0415 invalid ABS/ESP data
Plausibility: wheel speeds, power/grounds, coding, CAN.
P2293 fuel pressure regulator
Commanded vs actual pressure control checks.
P2015 intake runner position
Runner flap linkage, actuator, and sensor checks.
P0299 underboost
Boost too low (leaks, control, or turbo efficiency).
P0234 overboost
Boost too high (turbo control).
P2106 forced limited power
ETC/throttle limp mode workflow.
P0117 / P0118 coolant temp
ECT plausibility + wiring checks.
P0700 TCM request
Read TCM codes first (request code).
U0101 TCM communication
Power/ground + CAN checks.
P2458 DPF regen duration
Why regens run too long.
P0016 crank/cam correlation
Timing plausibility decision flow.
P2270 O2 signal stuck lean
Exhaust leak vs sensor/wiring.
P0500 vehicle speed sensor
VSS vs wheel speed checks.
P0606 ECU/PCM processor
Power/grounds before modules.
U0073 CAN bus off
Physical layer triage.
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