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P1194

ECM PCM A D Converter.

  • Mazda
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
1
AreaFuel and air metering
94
FaultThe specific fault in that area

What it means

On a Mazda, P1194 points to a fault in the analogue-to-digital converter inside the engine control module (ECM/PCM). The converter turns sensor voltages into digital values the processor can use. The module has seen a result from its own converter that failed its internal self-check or was out of range, so it cannot trust the readings it is working from.

Symptoms

  • Malfunction indicator lamp on
  • Erratic or poor running, hesitation or surging
  • Rough or unstable idle
  • Engine stalling or hard starting
  • Poor fuel economy
  • Other unrelated codes stored at the same time

Possible causes

  • Internal fault in the ECM/PCM converter circuitrylikely
  • Poor or corroded power or earth connections to the modulelikely
  • Low or unstable battery or charging system voltage affecting the module's reference voltagespossible
  • Damaged wiring or connector pins at the module, including water ingresspossible
  • A shorted sensor or wiring pulling down the shared sensor reference supplypossible
  • Outdated or faulty ECM/PCM software calibration, if a manufacturer bulletin applies to the modelrare

How to diagnose

  1. Read all stored and pending codes and note the freeze frame data (engine load, temperature, voltage) to see the conditions when it set.
  2. Check battery condition and charging voltage, as low or noisy voltage can upset the module's internal checks.
  3. Inspect the ECM/PCM connectors, main relay, fuses, and power and earth connections for corrosion, looseness, heat damage or moisture.
  4. Look over the wiring harness near the module for chafing, rodent damage and previous repairs.
  5. Clear the code, then road test and recheck to see whether it returns immediately or only under certain conditions such as vibration or damp.
  6. Check for other sensor circuit codes and measure the sensor reference voltage to rule out a shorted sensor dragging it down.
  7. Check whether a software update or technical bulletin exists for the specific model and engine.
  8. If everything else checks out and the code returns, test the module supply and signals to confirm a module fault before replacing it.

How to fix

  • Repair or clean corroded, loose or damaged power and earth connections at the module.
  • Repair damaged wiring or connector terminals and deal with any water ingress.
  • Restore the battery or charging system to proper condition if voltage is the cause.
  • Repair or replace any sensor or wiring shorting the reference supply.
  • Update the ECM/PCM calibration where an applicable update is known to address this fault.
  • Replace or repair the ECM/PCM, then program or adapt it as the model requires, once the module is confirmed faulty.

Can I keep driving?

Medium severity

The car may drive normally or may run badly, but the module is working with data it cannot fully trust, so book it in soon. Stop driving if it stalls, runs very poorly or goes into limp mode.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

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