Fault Code Reader for the Lucas ‘Hotwire’ ECU

This small unit, measuring 100mm x 50mm x 25mm, has been developed to replace the now obsolete Land Rover ‘on board diagnostic display’ (LR part number PRC 7067), enabling the home mechanic to easily diagnose engine problems which would either require an expensive visit to a garage, or the costly replacement of each component of the EFI system part by part until the fault has been rectified.

The code reader has been uniquely designed for the Lucas 14CUX engine management system, more commonly known as the Lucas ‘hotwire’ ECU, fitted to some variants of the Rover V8 engine.  Since its introduction in about 1989, it has been fitted to a range of Land Rovers, Range Rovers, the TVR Griffith and Chimaera, as well as a number of other vehicles, Morgan and Marcos for example.

The unit simply connects to a black rectangular 4-pin socket found in the wiring loom near to the ECU (see photo below).  NOTE - that it is important to check that such a connector is available as it is not present on a few early models, such as some early 1992 TVR Griffiths - PLEASE CHECK before buying.  Later TVR’s – we believe all Chimaeras and later Griffiths should be equipped with this connector.

Operating Instructions:-

To use the reader, simply connect to the black 4-pin socket – ensuring the connector is the correct way round.  Once connected, switch on the ignition, and the red power LED should be illuminated, along with any fault codes if present. Some versions of the ECU allow more than one code to be stored. To check for more codes, disconnect the unit with the engine running, wait 5 seconds, then reconnect the unit.  Turn off the ignition, wait until the main relay drops out (you should hear a click after 10 seconds or so), then turn the ignition back on.  The next fault code should be displayed if there is one present. (otherwise the first code will remain).   To clear the fault codes, disconnect the main ECU plug for 30 seconds or so then re-connect.  Note that if the fault code reader is used after an ECU reset, a 02 code will be generated – this means that the ECU power has been lost.  See the table below for details of all the fault codes. Note that the majority of these codes are only present on cars fitted with catalytic converters so the reader is more useful on these vehicles. 

Price:  Only £94.99 plus £4.00 p&p (UK) or £9.00 (EU).  This represents a significant saving over the original retail price of £123 + VAT for the original Land Rover PRC 7067 unit which has been discontinued.

UK Orders:

EU Orders:

(Stock status:- made to order (5 day turnaround). Please e-mail before ordering or to request futher details. Alternatively use our enquiry form)

Fault Code List

Code	Description	Comments
02	ECU Supply has been disconnected	Normal code to get after ECU has been reset.  May indicate supply problems if ECU has not been reset recently.  Code will be cleared if the ignition is turned on for 30 seconds or so
03	Data corrupted.	Corrupted data in ECU.  Reset ECU and test drive again.
12	Airflow meter out of range	Possible faulty airflow meter or connection/wiring fault.
14	Coolant thermistor out of range	Possible faulty coolant thermistor or connection/wiring fault.
15	Fuel thermistor out of range	Possible faulty coolant thermistor or connection/wiring fault.
17	Throttle pot out of range	Possible faulty throttle potentiometer / incorrect setting or connection/wiring fault.
18	Throttle pot output too high with low airflow	Major air leak between airflow meter and intake plenum.  Possible faulty airflow meter or throttle potentiometer or wiring/connections to either.
19	Throttle sensor output too low with high airflow	Possible faulty airflow meter or throttle potentiometer or wiring/connections to either.
21	Tune resistor out of range	Tune resistor has become disconnected / damaged.
23	Low fuel pressure	Possible faulty fuel pump/ blocked filter or faulty fuel pressure regulator. VALID FOR CAT CARS ONLY.
25	Misfire at full load	A misfire has been detected while engine under heavy throttle and during high airflow meter readings.  Check coil/plugs/leads/ distributor and ignition module.  Code means that lambda sensors have detected a rich condition under load.  Also see codes 40 and 50. VALID FOR CAT CARS ONLY.
28	Air leak	Air leak around intake plenum.  Check all hoses/ injector seals etc.
29	Checksum error	ECU fault.  Try resetting ECU and test driving again.  If fault code returns ECU may be faulty.  NOTE – any other codes generated should be ignored.
34	Fuelling fault in nearside injector bank	For cylinders 1-3-5-7 Possible injector, lambda sensor fault or wiring / connection fault to either.   Blocked injector(s) or air leak at injector /inlet manifold.  VALID FOR CAT CARS ONLY.
36	Fuelling fault in offside injector bank	For cylinders 2-4-6-8. Possible injector, lambda sensor fault or wiring / connection fault to either.   Blocked injector(s) or air leak at injector /inlet manifold.  VALID FOR CAT CARS ONLY.
40	Misfire on nearside bank	Misfire on 1-3-5-7 cylinders only.  Nearside lambda sensor has detected a fault (or fault in lambda sensor circuit). VALID FOR CAT CARS ONLY
44	Offside lambda sensor out of range	Possible faulty lambda sensor or wiring/connection fault.  See section 5 below for check. If in conjunction with code 45 then suspect lambda heater circuit.  VALID FOR CAT CARS ONLY
45	Nearside lambda sensor out of range	Possible faulty lambda sensor or wiring/connection fault.  See section 5 below for check.  If in conjunction with code 44 then suspect lambda heater circuit.  VALID FOR CAT CARS ONLY
48	Stepper motor fully open below 500rpm or fully closed above 750rpm.	Possible faulty stepper motor or wiring connections.  Stepper motor needs cleaning / is jammed.  Incorrectly set idle adjustment screw.  Incorrectly set throttle butterfly.  Misfire or rough running because of other faults.
50	Misfire on offside bank	Misfire on 2-4-6-8 cylinders only.  Offside lambda sensor has detected a fault (or fault in lambda sensor circuit). VALID FOR CAT CARS ONLY
58	ECU cannot distinguish between codes 23 and 28	Fault maybe either due to code 23 or 28.
59	Same as 58 or fuel thermistor out of range.	Documentation seems to vary here.  Code either means same as 58, or faulty fuel thermistor or wiring / connector fault.
68	Road speed sensor too low at medium rpm and high airflow	Possible speed sensor or wiring/ connection fault.
88	Power-up check / purge valve fault.	Sometimes shown on power up (CAT and NON-CAT CARS ) or could also indicate purge valve fault with carbon canister system.  (CAT CARS ONLY)