P0372
Timing Reference High Resolution Signal A Too Few Pulses.
- Generic
- Powertrain
- Generic code
- High severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 3
- AreaIgnition system or misfire
- 72
- FaultThe specific fault in that area
What it means
P0372 means the engine control unit has seen too few pulses from the high resolution timing reference signal (signal A) compared with what it expects for the engine speed or crank rotation. This signal is normally derived from the crankshaft position sensor and its reluctor or trigger wheel, and is used for precise timing and misfire detection. The exact signal arrangement and which sensor circuit is 'A' depends on the vehicle and engine.
Symptoms
- Malfunction indicator lamp on
- Engine misfiring or running roughly
- Hard starting or long cranking
- Intermittent stalling or cutting out
- Loss of power or poor acceleration
- Misfire codes stored alongside the fault
Possible causes
- Faulty or contaminated crankshaft position sensor, or a sensor with an incorrect air gaplikely
- Damaged wiring, poor connector contact or corrosion in the sensor circuit, including short or open circuitslikely
- Damaged, dirty or loose reluctor or trigger wheel, with missing or distorted teeth or magnetic debrispossible
- Electrical interference from poor earths, damaged ignition components or faulty charging systempossible
- Crankshaft and camshaft timing out of correlation, such as a stretched chain or slipped belt (model dependent)possible
- Fault within the engine control unit's signal input circuitrare
How to diagnose
- Read all stored codes and freeze frame data, noting engine speed, load and temperature when the fault set, and check for related crank, cam or misfire codes.
- Visually inspect the crankshaft sensor, its wiring and connector for chafing, oil contamination, heat damage, corrosion and loose fitting.
- Check battery condition, charging voltage and engine earth connections, as poor supply or earths can distort the signal.
- With a scan tool, watch live engine speed while cranking and check that a signal is present and steady, comparing crank and cam data if available.
- Check the sensor's supply, earth and signal circuits for continuity, shorts and resistance against the manufacturer's data for that engine.
- Inspect the sensor tip for metal debris and the reluctor wheel for damage, looseness or missing teeth, where access allows.
- Look at the crank signal pattern on an oscilloscope, checking for dropouts, noise or irregular amplitude.
- Check timing correlation using the manufacturer's procedure if the signal looks sound but the fault persists.
How to fix
- Replace the crankshaft position sensor if it is faulty, and set the air gap or fit it correctly as specified.
- Repair or replace damaged wiring, terminals or connectors in the sensor circuit.
- Clean off debris or replace a damaged or loose reluctor wheel or related component.
- Correct poor earths, battery or charging faults that cause signal interference.
- Correct the engine timing and replace worn timing components if correlation is wrong.
- Check for a software update only if the manufacturer lists an outdated calibration as a known cause for this fault, and replace the control unit only after all else is ruled out.
Can I keep driving?
Avoid driving if the engine is misfiring badly, stalling or cutting out, as this is unsafe and unburnt fuel can damage the catalytic converter. Have it checked promptly before further use.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.