2001 Honda Civic 1

It sounds to me like you are having issues with your MAP sensor which did come on this year of car. What all were the codes that the car was throwing? You need to find out what codes the ECU is throwing so you can diagnose what is wrong with the car. You can do that by following these steps here-

1.
Turn the engine OFF. Locate the 16P, OBDII Data Link Connector (DLC) under the driver's side dash. In the Civic it is in the vicinity of your right knee when you are driving. Use a jumper wire to connect terminals 4 and 9 of the DLC. IMPORTANT: Make sure you are connecting only the correct terminals as shown, otherwise you risk causing electrical damage to the ECU.

2.
Turn the ignition key to the ON (II) position, but do not start the engine.

3.
Carefully observe the CEL. It will flash in a distinct manner to display any DTCs that are store. If there are no codes stored, the CEL will not flash. The pattern of flashes indicates a one- or two-digit numeric code. The first digit of the code is represented by long flashes. The second digit of the code is represented by short flashes. A zero is represented by a brief pause. For example, four long flashes followed by five short flashes is code 45. One long flash followed by a pause is code 10.

4.
If there is more than one DTC stored, the CEL will display them in sequence, then it will continue to repeat all the codes after they have been displayed one time. Record and double-check all codes displayed.

5.
Look up the meaning of the codes retrieved on the DTC Index Page. Note that the one- or two-digit CEL codes correspond to more detailed four-digit OBDII codes.

6.
Clearing the codes: If you wish to clear the stored DTCs and reset the ECU, remove the #6 fuse (15A) in the underhood fusebox for at least 10 seconds. However, if you are going to take your vehicle to a professional mechanic for repair, it is better to leave the DTCs in the ECU so that they can read and troubleshoot them with an OBDII scan tool or Honda PGM console.

Codes are as follows:

1 O2A - Oxygen sensor #1
2 O2B - Oxygen sensor #2
3 MAP - manifold absolute pressure sensor
4 CKP - crank position sensor
5 MAP - manifold absolute pressure sensor
6 ECT - water temperature sensor
7 TPS - throttle position sensor
8 TDC - top dead centre sensor
9 CYP - cylinder sensor
10 IAT - intake air temperature sensor
12 EGR - exhaust gas recirculation lift valve
13 BARO - atmospheric pressure sensor
14 IAC (EACV) - idle air control valve
15 Ignition output signal
16 Fuel injectors
17 VSS - speed sensor
19 Automatic transmission lockup control valve
20 Electrical load detector
21 VTEC spool solenoid valve
22 VTEC pressure valve
23 Knock sensor
30 Automatic transmission A signal
31 Automatic transmission B signal
36 traction control found on JDM ecu's
38 Secondary vtec solenoid on JDM 3 stage D15B Vtec ECUs (P2J)
41 Primary oxygen sensor heater
43 Fuel supply system
45 Fuel system too rich or lean
48 LAF - lean air fuel sensor
54 CKF - crank fluctuation sensor
58 TDC sensor #2
61 Primary oxygen sensor
63 Secondary oxygen sensor circuit
65 Secondary oxygen sensor heater wire (black wires)
67 Cat Converter
70 Automatic transmission problem
71 random misfire cylinder 1
72 random misfire cylinder 2
73 random misfire cylinder 3
74 random misfire cylinder 4
80 EGR Valve/Line
86 ECT sensor - Cooling System
90 Evaporative Emission Control System Leak
91 Fuel Tank pressure sensor
92 EVAP Solenoid/Valve/Vacuum Lines

Also, what modifications/work has been done to the car recently?

Check for bad ground circuit for the ECU and also ensure all fuses are good. At DLC check for battery voltage at pin # 16.

Use a jumper wire between # 4 and # 9 and turn ignition switch on. Note if the check engine flashes trouble codes.

Use a DVOM and check # 9 for voltage with ignition switch turned on. If no voltage is present, either the circuit from PCM is open or you have a bad PCM.

That indicates a faulty PCM.