P02E8

Diesel Intake Air Flow Position Sensor Circuit Low

P02E8 is a generic OBD-II powertrain diagnostic trouble code: Diesel Intake Air Flow Position Sensor Circuit Low. It is logged by the engine control unit when the air/maf monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P02E8
Group
Powertrain
System
Air/MAF
Severity
Warning (MIL on, possible limp mode)
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What P02E8 means

P02E8 is set when the PCM detects a higher-than-expected voltage on the cylinder 4 fuel injector driver circuit during normal operation. This circuit-high condition most commonly results from an open circuit that prevents the injector driver from pulling the circuit to the low-voltage state needed to energise the solenoid, or from a short to battery voltage on the control wire.

An open injector circuit on cylinder 4 means no fuel is delivered to that cylinder, causing a complete misfire. The crankshaft position sensor will detect the resulting RPM drop or acceleration anomaly, and the ECM may store an associated misfire code alongside P02E8. Continued operation with no fuelling on cylinder 4 risks catalyst damage from the excess oxygen and residual fuel passing through.

The diagnostic process should start with simple physical inspection of the cylinder 4 injector connector and wiring, since open circuits are most frequently caused by connector failures or broken wires. Measuring injector solenoid resistance quickly confirms whether the injector itself has an open winding. Advanced testing with a lab scope can confirm the driver channel response after physical repairs are completed.

Common causes

Most-frequently reported root causes when P02E8 is logged.

  • 1
    Open circuit in the cylinder 4 injector harness.
  • 2
    Disconnected injector connector or backed-out connector pin.
  • 3
    Open solenoid winding inside the cylinder 4 injector.
  • 4
    Short to battery voltage on the injector control circuit.
  • 5
    Blown fuse or failed relay supplying injector power.
  • 6
    High-resistance corrosion at connector pins creating an effective open.
  • 7
    PCM driver output failure leaving the circuit at a high-voltage state.

Symptoms drivers notice

MIL on with cylinder 4 misfire code typically present simultaneously.
Noticeable vibration and rough running from loss of cylinder 4 contribution.
Rich or fuel-smell exhaust from unburned mixture on the misfiring cylinder.
Possible reduction in engine power and drivability.
Risk of catalytic converter overtemperature with prolonged misfire.

How to diagnose P02E8

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and record all stored codes and freeze frame data.
  2. 2
    Inspect the cylinder 4 injector electrical connector for disconnection, backed-out pins, or visible corrosion.
  3. 3
    Test wiring harness continuity from the PCM connector to the injector connector on both signal and power wires.
  4. 4
    Measure the cylinder 4 injector solenoid resistance at the injector pins to check for an open winding.
  5. 5
    With the PCM connector unplugged, check the signal wire for any voltage present indicating a short to power.
  6. 6
    Confirm injector fuse and relay are intact and providing correct supply voltage.
  7. 7
    Replace the injector if the solenoid is open; repair or replace wiring if the fault is in the harness or connector.

Related powertrain codes

Frequently asked questions

Can P02E8 be caused by a dead battery or low voltage?

Severe voltage drops can cause temporary circuit anomalies, but a persistent P02E8 at normal voltage indicates a genuine open or short-to-power fault.

Is P02E8 the same as a no-injector-pulse condition?

Effectively yes for cylinder 4: with an open circuit the solenoid cannot receive a current pulse, so no injection occurs.

What is the relationship between P02E7 and P02E8?

P02E7 is a low/short-to-ground fault on cylinder 4; P02E8 is the opposite, a high/open or short-to-power fault on the same circuit.

After replacing the injector, do I need to relearn anything?

On most port injection systems no relearn is needed. On direct injection systems with injector-specific correction factors, check whether the calibration requires an injector quantity adaptation reset.

Disabling P02E8 in software

RaceTune can permanently disable P02E8 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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