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P1202 Injector Circuit Fault (Cylinder 2) — Causes & Fix

Updated for 2026 diagnostics & repair guidance

P1202 at a Glance

What it means

Manufacturer-specific injector circuit fault for cylinder 2 (P1-series equivalent of P0202).

Most common cause

Injector solenoid resistance out of specification, wiring short, or connector corrosion.

Severity

Moderate to serious — the ECU may cut fuel to cylinder 2, causing a misfire.

Can you drive?

Short distances only. Prolonged driving risks DPF and catalytic converter damage.

Typical repair cost

£100-£350 for injector replacement; £40-£100 for wiring repair.

What Does P1202 Mean?

P1202 is a manufacturer-defined (P1-series) injector circuit code for cylinder 2, used by several makes — notably Ford and PSA diesels — alongside or instead of the generic P0202. The diagnosis is identical: coil resistance, wiring and connector checks, then a swap test to confirm whether the injector or the circuit is at fault.

Common Causes

Injector-Related Causes

Injector solenoid resistance out of specification

The injector coil has degraded with heat and age so its resistance no longer matches the ECU's expected window. Most common on engines over 80,000 miles.

Other Possible Causes

Wiring short or break to cylinder 2 injector

A chafed or corroded harness section between the ECU and cylinder 2 injector pulls the measured voltage low.

Corroded injector connector

Water ingress at the injector plug creates resistance that skews the circuit reading.

ECU injector driver fault

The output transistor driving this injector has failed. Less common — verify the injector and loom first.

Symptoms Drivers Notice

  • Misfire from cylinder 2, most obvious at idle
  • Engine management light on
  • Loss of power and rough running
  • Increased fuel consumption

Vehicles Commonly Affected

Can You Still Drive with P1202?

Driving short distances is usually possible but the engine will misfire and unburned fuel can damage the DPF and catalyst. Have the circuit tested promptly.

How Mechanics Diagnose P1202

  1. 1

    Read freeze-frame data

    Confirm which cylinder logged the fault and the conditions stored with it.

  2. 2

    Measure injector coil resistance

    Test at the cylinder 2 injector plug and compare the reading with specification.

  3. 3

    Inspect the harness and connector

    Wiggle-test the loom section and connector for chafing or corrosion.

  4. 4

    Swap-test the injector

    Move the injector to a neighbouring cylinder — if the code follows the injector, the injector is at fault.

  5. 5

    Verify the ECU driver output

    Check the ECU output stage only after the injector and loom test clean.

Repair Solutions & Costs

Repair the wiring or connector

£40–£100

Repair or replace the damaged harness section or corroded connector.

Replace the cylinder 2 injector

£100–£350Recommended

Fit a tested remanufactured unit if the coil is out of specification.

Code the replacement injector

Write the injector calibration code to the ECU following the manufacturer procedure.

Replacing injectors? Browse our remanufactured diesel injectors, reconditioned injectors or refurbished diesel injectors — all bench-tested with a 12-month warranty.

When Injector Replacement Is Required

If the injector coil resistance is out of specification or the fault follows the injector in a swap test, the injector must be replaced — coil failure cannot be repaired in situ.

Compatible Remanufactured Injectors

OEM bench-tested injectors for engines affected by P1202 — verified pricing, 12-month warranty, free UK delivery.

Compatible Injector Part Numbers

6 injectors compatible with engines affected by P1202.

Cross Reference Numbers

OEM and alternative part numbers for injectors affected by P1202.

Affected Vehicle & Engine Combinations

Trusted Injector Families for These Engines

Verified remanufactured injector families fitted to engines documented to log P1202.

Need a Replacement Injector?

UK-tested remanufactured injectors with 12-month warranty. Search by engine code or vehicle registration.

OEM tested & calibrated12-month warrantyFree UK deliveryNo coding required (most models)

Need it fast? Same-day dispatch on in-stock injectors.

Order before 2pm for next working day delivery (UK mainland). Call us on 020 3355 6581.

Engine-Specific Guides

Frequently Asked Questions

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Why It Happens

Common-rail injectors live at extreme pressures with clearances measured in microns. Fuel quality, heat cycles and mileage wear the internal control valve and nozzle: back-leak rises, spray patterns deteriorate and delivery drifts from calibration. Most 'engine' complaints on high-mileage diesels trace back to this gradual injector wear.

Professional Diagnosis

Workshops follow a fixed order: scan for codes and freeze-frame data, compare requested vs actual rail pressure on live data, read cylinder balance corrections, then run a comparative leak-off test. That sequence identifies the faulty injector without guesswork — and prevents needlessly replacing pumps, sensors or the wrong injector.

Typical Workshop Findings

The most frequent findings are: one injector returning several times the leak-off volume of its neighbours; carbon build-up from a failed copper washer; corroded injector connectors; and missing injector coding after a previous repair. Genuine high-pressure pump failures are rarer than back-leak faults that mimic them.

When to Replace Injectors

Replace when testing proves internal wear: leak-off clearly above the other injectors, balance corrections at their limits, or a failed bench test. Cleaning and additives cannot restore worn internal clearances. Bench-tested remanufactured injectors restore original calibration at a fraction of the new price — always coded to the ECU where the engine requires it.

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